Article

A Liquid Chromatography-Tandem Mass Spectrometry Multiresidue Method for Quantification of Specific Metabolites of Organophosphorus Pesticides, Synthetic Pyrethroids, Selected Herbicides, and DEET in Human Urine

June 2004
Analytical Chemistry 76(9):2453-61

June 2004
76(9):2453-61

DOI:10.1021/ac0355404

Source
PubMed

Authors:

Johnny Nguyen

University of Texas at Dallas

Show all 8 authorsHide

The ability to estimate low-dose human exposure to commonly used pesticides often is requested in epidemiologic studies. Therefore, fast and robust methods are necessary that can measure many analytes in the same sample. We have developed a method for high-throughput analysis of 19 markers of commonly used pesticides in human urine. The analytes were seven specific metabolites of organophosphorus pesticides, five metabolites of synthetic pyrethroids, six herbicides or their metabolites, and one insect repellant. Human urine (2 mL) was spiked with stable isotopically labeled analogues of the analytes, enzymatically hydrolyzed, extracted using solid-phase extraction, concentrated, and analyzed using high-performance liquid chromatography-tandem mass spectrometry. The sample was divided into two portions and analyzed on two different mass spectrometers, one using atmospheric pressure chemical ionization (APCI) and the other using turbo ion spray atmospheric pressure ionization (TIS). All analytes except the pyrethroid metabolites were analyzed using APCI. The detection limits for all analytes ranged from 0.1 to 1.5 ng/mL of urine, with the majority (17) below 0.5 ng/mL. The analytical precision for the different analytes, estimated as both the within-day and between-day variation, was 3-14 and 4-19%, respectively. The extraction recoveries of the analytes ranged from 68 to 114%. The throughput, including calibration standards and quality control samples, is approximately 50 samples a day. However, the analysis time with the TIS application is much shorter, and if only pyrethroid metabolite data are of interest, the throughput can be increased to 100-150 samples/day.

Literature review and evaluation of biomarkers, matrices and analytical methods for chemicals selected in the research program Human Biomonitoring for the European Union (HBM4EU)

Article

Aug 2022
ENVIRON INT

Humans are potentially exposed to a large amount of chemicals present in the environment and in the workplace. In the European Human Biomonitoring initiative (Human Biomonitoring for the European Union = HBM4EU), acrylamide, mycotoxins (aflatoxin B1, deoxynivalenol, fumonisin B1), diisocyanates (4,4’-methylenediphenyl diisocyanate, 2,4- and 2,6-toluene diisocyanate), and pyrethroids were included among the prioritized chemicals of concern for human health. For the present literature review, the analytical methods used in worldwide biomonitoring studies for these compounds were collected and presented in comprehensive tables, including the following parameter: determined biomarker, matrix, sample amount, work-up procedure, available laboratory quality assurance and quality assessment information, analytical techniques, and limit of detection. Based on the data presented in these tables, the most suitable methods were recommended. According to the paradigm of biomonitoring, the information about two different biomarkers of exposure was evaluated: a) internal dose = parent compounds and metabolites in urine and blood; and b) the biologically effective = dose measured as blood protein adducts. Urine was the preferred matrix used for deoxynivalenol, fumonisin B1, and pyrethroids (biomarkers of internal dose). Markers of the biological effective dose were determined as hemoglobin adducts for diisocyanates and acrylamide, and as serum-albumin-adducts of aflatoxin B1 and diisocyanates. The analyses and quantitation of the protein adducts in blood or the metabolites in urine were mostly performed with LC-MS/MS or GC-MS in the presence of isotope-labeled internal standards. This review also addresses the critical aspects of the application, use and selection of biomarkers. For future biomonitoring studies, a more comprehensive approach is discussed to broaden the selection of compounds.

Validated single urinary assay designed for exposomic multi-class biomarkers of common environmental exposures

Article

Jun 2022

Epidemiological studies often call for analytical methods that use a small biospecimen volume to quantify trace level exposures to environmental chemical mixtures. Currently, as many as 150 polar metabolites of environmental chemicals have been found in urine. Therefore, we developed a multi-class method for quantitation of biomarkers in urine. A single sample preparation followed by three LC injections was optimized in a proof-of-approach for a multi-class method. The assay was validated to quantify 50 biomarkers of exposure in urine, belonging to 7 chemical classes and 16 sub-classes. The classes represent metabolites of 12 personal care and consumer product chemicals (PCPs), 5 polycyclic aromatic hydrocarbons (PAHs), 5 organophosphate flame retardants (OPFRs), 18 pesticides, 5 volatile organic compounds (VOCs), 4 tobacco alkaloids, and 1 drug of abuse. Human urine (0.2 mL) was spiked with isotope-labeled internal standards, enzymatically deconjugated, extracted by solid-phase extraction, and analyzed using high-performance liquid chromatography-tandem mass spectrometry. The methanol eluate from the cleanup was split in half and the first half analyzed for PCPs, PAH, and OPFR on a Betasil C18 column; and pesticides and VOC on a Hypersil Gold AQ column. The second half was analyzed for tobacco smoke metabolites and a drug of abuse on a Synergi Polar RP column. Limits of detection ranged from 0.01 to 1.0 ng/mL of urine, with the majority ≤0.5 ng/mL (42/50). Analytical precision, estimated as relative standard deviation of intra- and inter-batch uncertainty, variabilities, was <20%. Extraction recoveries ranged from 83 to 109%. Results from the optimized multi-class method were qualified in formal international proficiency testing programs. Further method customization options were explored and method expansion was demonstrated by inclusion of up to 101 analytes of endo- and exogenous chemicals. This exposome-scale assay is being used for population studies with savings of assay costs and biospecimens, providing both quantitative results and the discovery of unexpected exposures.

Assessment of Preschool Children’s Exposure Levels to Organophosphate and Pyrethroid Pesticide: A Human Biomonitoring Study in Two Turkish Provinces

Article

Full-text available

Mar 2023
ARCH ENVIRON CON TOX

Pesticides are products developed to prevent, destroy, repel or control certain forms of plant or animal life that are considered to be pests. However, now they are one of the critical risk factors threatening the environment, and they create a significant threat to the health of children. Organophosphate (OP) and pyrethroid (PYR) pesticides are widely used in Turkey as well as all over the world. The main focus of this presented study was to analyze the OP and PYR exposure levels in urine samples obtained from 3- to 6-year-old Turkish preschool children who live in the Ankara (n:132) and Mersin (n:54) provinces. In order to measure the concentrations of three nonspecific metabolites of PYR insecticides and four nonspecific and one specific metabolite of OPs, liquid chromatography–tandem mass spectrometry (LC–MS/MS) analyses were performed. The nonspecific PYR metabolite 3-phenoxybenzoic acid (3-PBA) found in 87.1% of samples (n = 162) and the specific OP metabolite 3,5,6-trichloro-2-pyridinol (TCPY) found in 60.2% of samples (n = 112) were the most frequently detected metabolites in all urine samples. The mean concentrations of 3-PBA and TCPY were 0.38 ± 0.8 and 0.11 ± 0.43 ng/g creatinine, respectively. Although due to the large individual variation no statistically significant differences were found between 3-PBA (p = 0.9969) and TCPY (p = 0.6558) urine levels in the two provinces, significant exposure differences were determined both between provinces and within the province in terms of gender. Risk assessment strategies performed in light of our findings do not disclose any proof of a possible health problems related to analyzed pesticide exposure in Turkish children.

Longitudinal Assessment of Chlorpyrifos Exposure in Farmers and Residents of an Italian Alpine Region

Article

Full-text available

Dec 2021

The aim of this study was to obtain a longitudinal evaluation of the exposure to chlorpyrifos (CP) and chlorpyrifos-methyl (CPM) in agricultural workers in South Tyrol and in a residential group living in the same area. CP and CPM are widely used pesticides in agriculture. Biological monitoring of CP and CPM exposure in humans can be achieved by analyzing urinary levels of 3,5,6-trichloro-2-pyridinol (TCPy). TCPy a metabolite of CP and CPM which is produced by a two-step metabolic transformation. Between May 14th, 2014 and March 16th, 2015 we conducted a longitudinal study on 28 farmers actively working in spray pesticide treatment and 43 non-farmers living in the same agricultural area of South Tyrol (Italy). Urine samples were collected at two time points: during the pesticide treatment period and in a temporally distant season that should guarantee metabolite clearance. We developed and validated a liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for the determination of urinary TCPy levels. During the treatment season, both farmers and residents showed higher TCPy levels (median = 6.8 and 6.73 ug/g creatinine, respectively) than during the non-treatment season (median = 2.54 and 3.22 ug/g creatinine, respectively), suggesting a similar effect of the pesticide spraying on both groups. However, the observed TCPy levels resulted in a daily CP and CPM intake well below the limits recommended by FAO/WHO. During the non-treatment season, non-farmers showed higher TCPy levels values than farmers, suggesting the existence of TCPy of other unmeasured sources of exposure not considered in this study. This suggests that, for a comprehensive evaluation of the risks associated with TCPy exposure, additional sources should be identified in addition to CP and CPM pesticides.

Pesticides, cancer, and oxidative stress: an application of machine learning to NHANES data

Article

Full-text available

Jan 2024

Background The large-scale application of pyrethroids and organophosphorus pesticides has great benefits for pest control. However, the increase of cancer incidence rate in recent years has also caused public concern about the health risks of pesticides. Hence, we utilized data from the National Health and Nutrition Examination Survey (NHANES) to assess the association and risk between pesticide exposure and several cancers, along with the comprehensive impact of oxidative stress. In this study, six cancers and six common pesticides were included to analyze their correlation and risk. And the levels of eight oxidative stress marks and two inflammatory markers were used for stratified analysis. Multiple logistic regression analysis was applied to estimate the odds ratio and 95% confidence intervals. Machine learning prediction models were established to evaluate the importance of different exposure factors. Results According to the data analyzed, each pesticide increased the risk of three to four out of six cancers on average. Iron, aspartate aminotransferase (AST), and gamma glutamyl transferase levels positively correlated with cancer risk in most cases of pesticide exposure. Except for demographic factors, factors such as AST, iron, and 3-phenoxybenzoic acid showed high contributions to the random forest model, which was consistent with our expectations. The receiver operating characteristic curve showed that the prediction model had sufficient accuracy (74.2%). Conclusion Our results indicated that specific pesticide exposure increased the risk of cancer, which may be mediated by various oxidative stress mechanisms. Additionally, some biochemical indicators have the potential to be screened for cancer prevention.

Blurred lines: Crossing the boundaries between the chemical exposome and the metabolome

Article

Full-text available

Dec 2023
CURR OPIN CHEM BIOL

The aetiology of every human disease lies in a combination of genetic and environmental factors, each contributing in varying proportions. While genomics investigates the former, a comparable holistic paradigm was proposed for environmental exposures in 2005, marking the onset of exposome research. Since then, the exposome definition has broadened to include a wide array of physical, chemical, and psychosocial factors that interact with the human body and potentially alter the epigenome, the transcriptome, the proteome, and the metab-olome. The chemical exposome, deeply intertwined with the metabolome, includes all small molecules originating from diet as well as pharmaceuticals, personal care and consumer products, or pollutants in air and water. The set of techniques to interrogate these exposures, primarily mass spectrometry and nuclear magnetic resonance spectroscopy, are also extensively used in metabolomics. Recent advances in untar-geted metabolomics using high resolution mass spectrometry have paved the way for the development of methods able to provide in depth characterisation of both the internal chemical exposome and the endogenous metabolome simultaneously. Herein we review the available tools, databases, and work-flows currently available for such work, and discuss how these can bridge the gap between the study of the metabolome and the exposome. Addresses

Prenatal exposure to persistent and non-persistent chemical mixtures and associations with adverse birth outcomes in the Atlanta African American Maternal-Child Cohort

Article

Full-text available

Feb 2023
J EXPO SCI ENV EPID

Background African Americans (AAs) experience higher rates of preterm birth and fetal growth restriction relative to other pregnant populations. Differential in utero exposure to environmental chemicals may partially explain these health disparities, as AAs are disproportionately exposed to environmental hazards. Objective We examined the individual and mixture effects of non-persistent chemicals and persistent organic pollutants (POPs) on gestational age at birth and birthweight for gestational age z-scores within a prospective cohort of pregnant AAs. Methods First-trimester serum and urine samples obtained from participants within the Atlanta African American Maternal-Child cohort were analyzed for 43 environmental chemicals, including per-and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides, pyrethroid insecticides, phthalates, bisphenol A, nicotine, and the primary metabolite of delta-9-tetrahydrocannabinol. Linear regression was used to estimate individual associations between chemicals and gestational age and birthweight z-scores (N ranging from 107 to 523). Mixture associations were estimated using quantile g-computation, principal component (PC) analyses, and hierarchical Bayesian kernel machine regression among complete cases (N = 86). Results Using quantile g-computation, increasing all chemical exposures by one quantile was modestly associated with a reduction in gestational age (mean change per quartile increase = −0.47, 95% CI = −1.56, 0.61) and birthweight z-scores (mean change per quartile increase = −0.49, 95% CI = −1.14, 0.15). All PCs were associated with a reduction in birthweight z-scores; associations were greatest in magnitude for the two PCs reflecting exposure to combined tobacco, insecticides, PBDEs, and phthalates. In single pollutant models, we observed inconsistent and largely non-significant associations. Signifance We conducted multiple targeted exposure assessment methods to quantify levels of environmental chemicals and leveraged mixture methods to quantify their joint effects on gestational age and birthweight z-scores. Our findings suggest that prenatal exposure to multiple classes of persistent and non-persistent chemicals is associated with reduced gestational age and birthweight z-scores in AAs. Impact African Americans (AAs) experience higher rates of preterm birth and fetal growth restriction relative to other pregnant populations. Differential in utero exposure to environmental chemicals may partially explain these health disparities, as AAs are disproportionately exposed to environmental hazards. In the present study, we analyzed serum and urine samples for levels of 43 environmental chemicals. We used quantile g-computation, principal component analysis, and BKMR to assess associations between chemical exposure mixtures and adverse birth outcomes. Our findings suggest that prenatal exposure to multiple classes of chemicals is associated with reduced birthweight z-scores, a proxy for fetal growth, in AAs.

Urinary pyrethroid metabolite and hearing threshold shifts of adults in the United States: A cross-sectional study

Article

Full-text available

Oct 2022
PLOS ONE

Hearing loss (HL) is a global health problem with a high prevalence and profound socioeconomic impact. Pyrethroids are one of the most commonly used insecticides. Although previous studies have reported the relationship between pyrethroids and neurotoxicity, little is known about the effect of pyrethroid exposure on the auditory system among the general population. This study is aimed to investigate the association of pyrethroid exposure with hearing threshold shifts of adults in the United States. A total of 726 adults, aged from 20 to 69 years from the 2011-2012 National Health and Nutrition Examination Survey (NHANES) data were included in the study. Urinary 3-phenoxybenzoic acid (3-PBA), a general pyrethroid metabolite, was used as a biomarker for pyrethroid exposure. HL was defined as a pure-tone average (PTA) at 0.5, 1, 2, 4 kHz ≥ 20 dB in the better ear. Analyses by using multivariate linear regressions were conducted to explore the associations of urinary 3-PBA with PTA hearing threshold shifts. There were no statistically significant correlations between Ln-transformed 3-PBA and either low-frequency or high-frequency hearing thresholds after adjusting for age, gender, race/ethnicity, education level, firearm noise exposure, occupational noise exposure, recreational noise exposure, serum cotinine, BMI, hypertension, and diabetes. However, associations of 3-PBA with both low-frequency and high-frequency hearing thresholds depended on age (P interaction < 0.0396 and 0.0017, respectively). Positive associations between Ln-transformed 3-PBA and both low-frequency and high-frequency hearing thresholds were observed in participants aged 20-39 years after adjusting confounders (β = 1.53, 95% CI: 0.04-3.01, and β = 3.14, 95% CI: 0.99-5.29, respectively) with the highest tertile (≥ 0.884 μg/g creatinine) of 3-PBA compared with the lowest tertile (< 0.407 μg/g creatinine). The possibility of interaction between 3-PBA and age on the hearing threshold shifts indicated that pyrethroid insecticides were prone to be more toxic to auditory system in younger adults than in older ones. Further studies will be required to confirm these findings.

Assessment of Preschool Children’s Exposure Levels to Organophosphate and Pyrethroid Pesticide : A Human Biomonitoring Study in Two Turkish Provinces

Preprint

Full-text available

Aug 2022

Pesticides are products that were developed for the benefit of humanity. However, now they are one of the critical risk factors threatening the environment, and they create a significant threat to the environmental health of children. Organophosphate (OP) and pyrethroid (PYR) pesticides are widely used in Turkey as well as all over the world. The main focus of this presented study was to analyze the OP and PYR exposure levels in urine samples obtained from 3–6 year old Turkish preschool children who lives in the Ankara (n:132) and Mersin (n:54) provinces. In order to conduct the determination of three non-specific metabolites of PYR insecticides and four non-specific and one specific metabolite of OPs LC-MS/MS quantitative analyses were employed. The non-specific PYR metabolite 3-phenoxybenzoic acid (3-PBA) (87.1%; n = 162) and the specific OP metabolite 3,5,6-Trichloro-2-pyridinol (TCPY) (60.2%; n = 112) were the most frequently detected metabolites in all urine samples. The mean concentrations of 3-PBA and TCPY were 0.38 ± 0.8 and 0.11 ± 0.43 ng/g creatinine, respectively. Although due to the large individual variation no statistically differences were found between 3-PBA (p = 0.9969) and TCPY (p = 0.6558) urine levels in the two provinces, significant exposure differences were determined both between provinces and within the province in terms of gender. Risk assessment strategies performed in light of our findings do not disclose any proof of a possible health problems related to analyzed pesticide exposure in Turkish children.

Informe técnico-científico sobre el uso e impactos del herbicida atrazina en Argentina

Book

Full-text available

Sep 2021

Investigation of Prenatal Pesticide Exposure and Neurodevelopmental Deficits in Northern, Thailand: A Longitudinal Birth Cohort Study (SAWASDEE Study) (Preprint)

Article

Full-text available

Jun 2021

Background: Prenatal exposure to pesticides has been linked to adverse neurodevelopmental outcomes. Gaps exist in the current literature about the timing and magnitude of exposures that result in these adverse outcomes. Objective: The Study of Asian Women and their Offspring's Development and Environmental Exposures (SAWASDEE) cohort was established to investigate the impact of prenatal exposure to pesticides on early indicators of cognitive and motor skills, inhibitory control, emotion regulation, and memory that have been found to be important in the development of subsequent neurobehavioral and neurodevelopmental diseases. The overarching goal is to find earlier predictors of potential adverse neurologic outcomes in order to enable earlier interventions that could result in better outcome prognoses. Methods: Recruitment of this prospective, longitudinal birth cohort began in July 2017 and was completed in June 2019 in Chom Thong and Fang, 2 farming districts in Chiang Mai Province in northern Thailand. Follow-up of the study participants is ongoing. During pregnancy, 7 questionnaires were administered. Time-resolved biospecimen samples were collected monthly (for urine) and during each trimester (for blood) during antenatal care visits. Medical records were abstracted. Infants were administered the NICU Network Neurobehavioral Scale (NNNS) test at 1 month of age. A total of 322 mother-child pairs completed the NNNS test. All children will be followed until 3 years of age and undergo a series of neurodevelopmental tests. We will complete several additional exposure related analyses. Results: A total of 1298 women were screened, and of those, 394 (30.35%) women were enrolled. The mean gestational age at enrollment was 9.9 weeks (SD 2.6). Differences in literacy were observed between Chom Thong and Fang participants. In Fang, about 54 of 105 (51.4%) participants reported being able to read in Thai compared to about 206 of 217 (94.9%) participants in Chom Thong. The percentages were comparable for reporting to be able to write in Thai. Conclusions: This longitudinal birth cohort study will inform risk assessment standards for pregnant women in Thailand and other countries. Building awareness of how insecticide exposure during specific windows of pregnancy affects the neurodevelopmental trajectories of children in developing countries is a specific need recognized by the World Health Organization. International registered report identifier (irrid): DERR1-10.2196/31696.

Prenatal maternal pesticide exposure in relation to sleep health of offspring during adolescence

Article

Aug 2021
ENVIRON RES

Study objectives The neurobiological processes involved in establishing sleep regulation are vulnerable to environmental exposures as early as seven weeks of gestation. Studies have linked. in utero pesticide exposure to childhood sleep-disordered breathing. However, the impact of in utero pesticide exposure on the sleep health of adolescents remains unexplored. Materials and methods Data from 137 mother-adolescent pairs from a Mexico City cohort were analyzed. We used maternal urinary 3-phenoxybenzoic acid (3-PBA, pyrethroid metabolite) and 3, 5, 6-trichloro-2-pyridinol (TCPy, chlorpyrifos metabolite) from trimester three to estimate in utero pesticide exposure. Among adolescents, we obtained repeated measures of objectively assessed sleep duration, midpoint, and fragmentation using wrist-actigraphy devices for 7 consecutive days in 2015 and 2017. Unstratified and sex-stratified associations between maternal urinary 3-PBA and TCPy and adolescent sleep measures were examined using linear mixed models. We also examined the interactive effects of maternal pesticide exposure and offspring sex on sleep outcomes. Results 3-PBA and TCPy were detected in 44.4% and 93% of urine samples, respectively. In adjusted models, we observed monotonic associations between TCPy with longer sleep duration and later sleep midpoint. Adjusted findings demonstrated that higher exposure to maternal TCPy was associated with longer sleep duration (p, trend = 0.01), and later sleep timing (p = 0.07). Findings from interaction tests between exposure and offspring sex were not statistically significant. Adjusted sex-stratified findings showed that the association between TCPy with duration and midpoint was evident only among female offspring; those in the highest tertile of exposure had a 59 min (95% CI: 12.2, 104.8) (p, trend = 0.004) longer sleep duration and a 0.6 h (95% CI: 0.01, 1.3) (p, trend = 0.01) later sleep midpoint. We found no significant associations between 3-PBA and sleep outcomes. Conclusion Although findings from interaction tests were not statistically significant, effect estimates demonstrated that associations between maternal pesticide exposure and longer sleep duration and later sleep timing were stronger in female offspring.

Association between pyrethroid exposure and cardiovascular disease: A national population-based cross-sectional study in the US

Article

Apr 2021

Objective Pyrethroids-containing products are widely used as commercial and household insecticides. While animal studies and clinical case reports have shown acute cardiovascular outcomes of pyrethroids exposure, little has been known on the effect of chronic pyrethroid exposure on cardiovascular disease (CVD). We aimed to examine the associations between chronic pyrethroid exposure and CVD in the US adults. Methods Cross-sectional data from the National Health and Nutrition Examination Survey 1999–2002 and 2007–2012 were analyzed. The exposure to pyrethroids was determined as the urinary level of 3-phenoxybenzoic acid (3-PBA), and CVD was ascertained based on self-reported physician diagnoses. Multivariable logistic regression models were fitted to evaluate associations of pyrethroid exposure with CVD, coronary heart disease (CHD), and stroke. Results Included were 6,471 participants with a mean age of 44.77 years (standard error, 0.39) for final analyses. The weighted prevalence of CVD, CHD, and stroke was 6.85%, 4.57% and 2.27%, respectively. With adjustments for major confounders, participants in the highest tertile of urinary 3-PBA had higher odds of CVD (odds ratio, 1.58; 95% confidence interval: 1.12, 2.23) and CHD (OR, 1.75; 95% CI: 1.17, 2.61) compared to those in the lowest tertile. There were linear associations for CVD (P for trend = 0.04) and CHD (P for trend = 0.02). However, no significant association was noted for stroke (1.29; 0.78, 2.16) in the main analyses. Conclusions 3-PBA was adversely associated with CVD and CHD in the US adults. Our findings highlight potential cardiovascular risk of chronic exposure to pyrethroids, and should be validated in large prospective studies in different populations in future.

Ion chromatography coupled with fluorescence/UV detector: A comprehensive review of its applications in pesticides and pharmaceutical drug analysis

Article

Full-text available

Dec 2020

Ion chromatography (IC) is a well-known technique for trace determination of inorganic ions and small organic acids. Recently, it has also appeared as a promising alternative to reverse phase chromatography for the determination of polar pesticides and pharmaceutical drugs in various sample matrices. Therefore, this study aims to provide a comprehensive overview of the application of IC coupled to fluorescence (FLD) or UV detector for the determination of pesticides and pharmaceutical drugs in samples from all walks of life. Apart from advantages and limitations, a short comparison of IC-FLD/UV with other techniques especially reverse-phase chromatography was drawn to envision future research efforts in this direction. Finally, several related areas such as IC hyphenation with different detectors (spectroscopic and spectrometer), miniaturization, automation, green chemistry, mobile phase, column, sample preparation, etc., were discussed to highlight its application for the determination of a wide range of analytes in the complex sample matrix.

Urinary concentrations of 2,4-D in repeated samples from 0−7 year old healthy children in central and south China

Article

Dec 2020
CHEMOSPHERE

Herbicide 2,4-Dichlorophenoxyacetic acid (2,4-D) and its analogues are widely used in agriculture. Although the occurrence of 2,4-D in urine has been widely reported in North America, it has scarcely been investigated in China, especially in young children. In addition, both in vivo and in vitro studies have shown that high-level 2,4-D exposure is associated with oxidative stress, but their association in a general sensitive population has rarely been studied. In this study, 2,4-D and its analogues were measured in 417 urine samples collected from 139 children aged 0–7 during the non-peak season of pesticide application in Wuhan, central China, and Shenzhen, south China. Each of them provided three samples in three consecutive days. An oxidative stress biomarker, 8-hydroxy-2-deoxyguanosine (8-OHdG), was also measured. The geometric mean (GM) of unconjugated urinary 2,4-D concentration was 0.10 μg/L (corrected by urinary specific gravity, SG-corrected). After β-glucuronidase hydrolysis, the GM of SG-corrected urinary 2,4-D was 0.15 μg/L, and the detection frequency was 100%. Moderate inter-day reproducibility was found within individuals, with an intraclass correlation coefficient of 0.68 for SG-corrected urinary deconjugated 2,4-D. The GM of estimated daily intake of 2,4-D was 6.05 ng/kg-bw/day. A significant positive correlation was found between urinary 2,4-D and 8-OHdG, whereas no association was found after SG-correction. This is the first study to characterize the occurrence of urinary 2,4-D, its inter-day reliability, and its association with urinary 8-OHdG in young children from China.

Residual determination of pyrethrins in Lycium barbarum (goji) by GC-MS/MS and a dietary risk assessment of Chinese goji consumption

Article

Jan 2020

An accurate and simple analytical approach for the determination of residues cinerin I, cinerin II, jasmolin I, jasmolin II, pyrethrin I and pyrethrin II (six active ingredients of pyrethrins) in fresh and dried goji berries was developed and validated for analysis by gas chromatography with tandem mass spectrometry. Good linearity (determination coefficient >0.99), accuracy (average recoveries of 88.3%–111.5%) and precision (intra- and inter-day relative standard deviations of 0.4%–8.3%) were obtained with the optimised determination method. The LODs and LOQs of the six analytes in two goji matrices were 0.24–2.1 µg/kg and 0.8–7 µg/kg, respectively. In a field trial, the terminal residual levels of pyrethrins (the sum of the concentrations of the six target analytes) in fresh and dried goji berry samples were <20–304 µg/kg at harvest, which could provide some information for the establishment of a maximum residue limit of pyrethrins on goji berries in China. Moreover, the risk assessment results indicated that because the risk quotient values were ≪100%, the potential dietary risk of pyrethrins on goji berries could be negligible for Chinese consumers. These detection and field results could provide some supporting data for the determination of pyrethrin residues in other crops and the proper application and safety assessment of pyrethrins in goji plants.

Surface functionalized cadmium telluride quantum dots for the optical detection and determination of herbicides

Article

Full-text available

Apr 2018
J MATER SCI-MATER EL

An optical sensor for detection of herbicides was developed through the functionalization of CdTe quantum dots (CdTe-QDs) with cysteamine hydrochloride. The functionalized CdTe-QDs was characterized with various physicochemical methods such as X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray analysis, Ultraviolet–visible and photoluminescence spectroscopies. The optical band gap of the functionalized CdTe-QDs as calculated by using Tauc plot was 3.75 eV. It was found that the fluorescence intensity of the functionalized CdTe-QDs quenched linearly in the presence of different herbicides according to the Stern–Volmer equation. Thus, the functionalized CdTe-QDs can be used as simple, rapid, inexpensive, and optical sensitive sensor for practical detection of herbicides.

Organophosphorus pesticide determination in biological specimens: bioanalytical and toxicological aspects

Article

Full-text available

Nov 2019
INT J LEGAL MED

Organophosphorus insecticides, such as parathion-ethyl, quinalphos, chlorpyrifos, chlorfenvinphos or diazinon, are still widely used for pest control on crops. These compounds are extremely toxic to humans, and, even though specific legislation exists that controls the use of these substances, the frequency of toxic and/or fatal events and the existing data suggest that they are still easily accessed and the knowledge associated to the risks is not well-recognized. For these reasons, the determination of the exposure to these compounds, their detection (and of their metabolites as well) in biological samples, is of great importance in clinical and forensic toxicology, and, therefore, the development of techniques for this evaluation is an important task for laboratories. Most confirmatory analyses use blood, serum, plasma and urine as biological samples and are performed by either gas chromatographic-mass spectrometric or liquid chromatographic-mass spectrometric instrumentation, which represents the gold standard in what concerns high sensitivity. This paper will not only address the physical–chemical and toxicological aspects of this class of compounds but also perform a comprehensive and critical review on the analytical methods available for their determination in biological specimens, with special focus on the latest instrumental developments and sample preparation approaches.

A fast and sensitive analytical procedure for monitoring of synthetic pyrethroid pesticides' metabolites in environmental water samples

Article

May 2019

In this paper, we report a simple, fast, and sensitive analytical procedure for monitoring of synthetic pyrethroid pesticides' (SPPs') metabolites in environmental water samples using a novel vortex-assisted salt-induced liquid-liquid microextraction (VA-SI-LLME) method coupled with liquid chromatography/tandem mass spectrometric (LC-MS/MS) analysis. VA-SI-LLME was carried out by taking 4 mL of sample solution followed by the addition of isopropanol and ethyl acetate (0.4 mL, 1:2, v/v) as a binary extraction solvent, and 4 g of ammonium sulfate for phase separation. Then, the mixture solution was vortex for 2 min and centrifuged for 3 min to collect the extractant and inject into LC-MS/MS for analysis. Experimental factors affecting the VA-SI-LLME including extraction solvent, extraction solvent volume, salt type, amount of salt, extraction time, and sample pH were completely optimized. The developed analytical method was validated, and the results exhibited good linearity in the concentration ranges between 0.01–100 ng mL ⁻¹ with the correlation coefficient (r ² ) >0.992 for the target SPPs' metabolites. Excellent limit of quantification and precision were achieved in the range between 0.01–0.1 ng mL ⁻¹ , and 1.55–5.06% (in terms relative standard deviation), respectively. The developed method was employed to determine the target SPPs' metabolites in tap, lake, river water, and influent wastewater samples collected in Kaohsiung city area, Taiwan. The extraction recoveries of spiked samples were satisfactory. Therefore, the presented method can be used as a potential alternative analytical procedure for monitoring of pesticides' metabolites in aqueous samples.

Nanostructured Diatom-ZrO2 composite as a selective and highly sensitive enzyme free electrochemical sensor for detection of methyl parathion

Article

Mar 2019
SENSOR ACTUAT B-CHEM

In the current work we report a simple and scalable technique for synthesis of ordered nanoporous Si-ZrO2 composite derived from the diatom Phaeodactylum tricornutum. The composite was well characterized using SEM, TEM-EDX, FTIR, TGA, BET and DLS. The diatom-ZrO2 was found to have a specific surface area of 140 m2/g, Si:Zr ratio of 1:4 and a particle size of 80 ± 2 nm. This composite was evaluated as an enzyme free electrochemical sensor towards the detection of methyl parathion (MP) and showed excellent sensing ability at extremely low detection limits of 54.3 pM and a linear concentration range of 3.4 nM to 64 µM. The diatom-ZrO2 composite was also found to be highly selective towards MP as shown by its resposne even in the presence of high concentrations of other interfering molecules and ions.

Simultaneous Determination of Pyrethroid, Organophosphate and Carbamate Metabolites in Human Urine by Gas Chromatography–Mass Spectrometry (GCMS)

Article

Full-text available

Mar 2019

We have developed a rapid, sensitive, and reliable method for simultaneous determination of the urinary metabolites of common insecticides in a single analytical run using gas chromatography–mass spectrometry (GCMS). Thirteen metabolites, one originating from carbamate, six from organophosphates, and seven from pyrethroids, were selected for method validation. Samples at different concentrations (0.5–15 µg/L) were prepared by mixing working solutions containing the analytes with blank urine. After acid hydrolysis for 45 min at 90 °C, samples were processed with liquid–liquid extraction and derivatization by N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide (MTBSTFA) before analysis on GCMS. The limits of detection for all thirteen analytes were below 0.1 µg/L. The recovery rates, evaluated at two concentrations (1, 10 µg/L), were found to be 90.48%, on average. The precision of multiple analyses at three different concentrations (0.5, 5, 15 µg/L) within one day or between 10 days was evaluated, and the resultant relative standard deviations were 8.1% or under. We also applied this method to analyze genuine urine samples collected from 30 human subjects, and successfully detected all the metabolites, with detection frequencies more than 50% for pyrethroid metabolites. In summary, this method is not only as good as others in performance, but is advantageous in terms of cost effectiveness and multiplicity of analytes.

Permethrin exposure from wearing fabric-treated military uniforms in high heat conditions under varying wear-time scenarios

Article

Full-text available

May 2020
J EXPO SCI ENV EPID

This study examined the effect of high-temperature conditions and uniform wear time durations (expeditionary, 33 h continuous wear; garrison, 3 days, 8 h/day wear) on permethrin exposure, assessed by urinary permethrin biomarkers, from wearing post-tailored, factory-treated military uniforms. Four group study sessions took place over separate 11-day periods, involving 33 male Soldiers. Group 1 (n = 10) and Group 2 (n = 8) participants wore a study-issued permethrin-treated Army uniform under high heat environment (35 °C, 40% relative humidity (rh)) and expeditionary and garrison wear-time conditions, respectively. For comparison, Group 3 (n = 7) and Group 4 (n = 8) participants wore study-issued permethrin-treated uniforms in cooler ambient conditions under operational and garrison wear-time conditions, respectively. Urinary biomarkers of permethrin (3-phenoxybenzoic acid, and the sum of cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid) were significantly higher under high temperature compared to ambient conditions, regardless of wear-time situations (Group 1 vs. Group 3; Group 2 vs. Group 4; p < 0.001, for both). Under high-temperature conditions, expeditionary (continuous) compared to garrison wear-time resulted in significantly (p < 0.001) higher urinary biomarker concentrations (Group 1 vs. Group 2). Differences related to wear-time under the ambient conditions (Group 3 vs. Group 4) were not statistically significant. Findings suggest that wearing permethrin-treated clothing in heat conditions results in higher internal dose of permethrin above that observed under ambient conditions.

A Prospective Study of Environmental Exposures and Early Biomarkers in Autism Spectrum Disorder: Design, Protocols, and Preliminary Data from the MARBLES Study

Article

Full-text available

Nov 2018

Background: Until recently, environmental factors in autism spectrum disorder (ASD) were largely ignored. Over the last decade, altered risks from lifestyle, medical, chemical, and other factors have emerged through various study designs: whole population cohorts linked to diagnostic and/or exposure-related databases, large case-control studies, and smaller cohorts of children at elevated risk for ASD. Objectives: This study aimed to introduce the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) prospective study and its goals, motivate the enhanced-risk cohort design, describe protocols and main exposures of interest, and present initial descriptive results for the study population. Methods: Families having one or more previous child with ASD were contacted before or during a pregnancy, and once the woman became pregnant, were invited to enroll. Data and biological samples were collected throughout pregnancy, at birth, and until the child's third birthday. Neurodevelopment was assessed longitudinally. The study began enrolling in 2006 and is ongoing. Results: As of 30 June 2018, 463 pregnant mothers have enrolled. Most mothers ([Formula: see text]) were thirty years of age or over, including 7.9% who are fourty years of age or over. The sample includes 22% Hispanic and another 25% nonHispanic Black, Asian, or multiracial participants; 24% were born outside the United States. Retention is high: 84% of participants whose pregnancies did not end in miscarriage completed the study or are still currently active. Among children evaluated at 36 months of age, 24% met criteria for ASD, and another 25% were assessed as nonASD nontypical development. Conclusion: Few environmental studies of ASD prospectively obtain early-life exposure measurements. The MARBLES study fills this gap with extensive data and specimen collection beginning in pregnancy and has achieved excellent retention in an ethnically diverse study population. The 24% familial recurrence risk is consistent with recent reported risks observed in large samples of siblings of children diagnosed with ASD. https://doi.org/10.1289/EHP535.

Rational Integration of Biomineralization, Microbial Surface Display, and Carbon Nanocomposites: Ultrasensitive and Selective Biosensor for Traces of Pesticides

Article

Oct 2018

Nowadays, the over misuse of organophosphate pesticides (OPP) has seriously threatened human health and environment, and it is challenging and indispensable to establish biosensor for supersensitive, reliable, and fast detection of traces of OPP in real samples. This work provides an interdisciplinary strategy for the construction of electrochemical OPP biosensor with supersensitivity, high selectivity, simple operation, and fast response. First, amino acid ionic liquid (AAIL) is used as stabilizer to dramatically improve the dispersibility of carbon nanotube (CNT) in the water phase, so that the obtained CNT@AAIL composites show good conductivity, biocompatibility, and electrocatalytic activity. Further, CNT@AAIL composites are employed to improve the conductivity and electrochemical activity of mineralized organophosphate hydrolase (OPH)‐fused cell (M‐Cell) with excellent catalytic activity for the fabrication of electrochemical biosensor. Based on synergistic effects of CNT@AAIL and M‐Cell, the constructed biosensor shows 2–8 orders of magnitude lower limit of detection (3 fmol L⁻¹) than those of reported OPP analytic methods. In addition, due to the specificity of OPH and detection at negative potential, the biosensor shows excellent selectivity. In addition, the biosensor also demonstrates the acceptable reliability for the traces of pesticides in real samples. This work will open an interdisciplinary avenue for supersensitive electrochemical biosensor.

Association of prenatal chlorpyrifos exposure with sexually dimorphic differences in anogenital distance among Thai farmworker children

Article

Jan 2024
ENVIRON RES

New sensitive LC-MS/MS method for the simultaneous determination of 13 phenolic and carboxylic acid pesticide biomarkers in human urine, including dicamba

Article

Oct 2023
CHEMOSPHERE

Online solid phase extraction high-performance liquid chromatography – Isotope dilution – Tandem mass spectrometry quantification of organophosphate pesticides, synthetic pyrethroids, and selected herbicide metabolites in human urine

Article

Aug 2023
CHEMOSPHERE

Analytical methods to quantify pesticide biomarkers in human population studies are critical for exposure assessment given the widespread use of pesticides for pest and weed control and their potential for affecting human health. We developed a method to quantify, in 0.2 mL of urine, concentrations of 10 pesticide biomarkers: four organophosphate insecticide metabolites (3,5,6-trichloro-2-pyridinol (TCPy), 2-isopropyl-6-methyl-4-pyrimidinol, para-nitrophenol, malathion dicarboxylic acid); five synthetic pyrethroid insecticide metabolites (4-fluoro-3-phenoxybenzoic acid, 3-phenoxybenzoic acid, cis and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCCA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid); and the herbicide 2,4-dichlorophenoxyacetic acid. The method is based on enzymatic hydrolysis of conjugated urinary metabolites, extraction and pre-concentration of the deconjugated metabolites using automated online solid-phase extraction, and separation and quantification using liquid chromatography-isotope dilution tandem mass spectrometry. Depending on the analyte, method detection limits were 0.1-0.6 ng/mL; mean accuracy, calculated as spike recoveries, was 91-102%, and total precision, given as percent variation coefficient, was 5.9-11.5%. Percent differences associated with three freeze-thaw cycles, 24-h benchtop storage, and short-term processed sample stability were <14%. METHOD: suitability was assessed by recurring successful participation in external quality assessment schemes and by analyzing samples from subjects with suspected exposure to pesticides (n = 40) or who self-reported consuming an organic diet (n = 50). Interquartile ranges were considerably lower for people consuming an organic diet than for those potentially exposed for cis-DCCA (0.37 ng/mL vs 0.75 ng/mL), trans-DCCA (0.88 ng/mL vs 1.78 ng/mL) and TCPy (1.81 ng/mL vs 2.48 ng/mL). This method requires one-fifth of the sample used in our previous method and is suitable for assessing background exposures to select pesticides in large human populations and for studies with limited sample volumes.

Screening strategy for 1210 exogenous chemicals in serum by two-dimensional liquid chromatography-mass spectrometry

Article

May 2023

Humans are at risk of exogenous exposure to exogenous chemicals. Challenges exist for the comprehensive monitoring of residues with different physical and chemical properties in serum. Here, an on-line two-dimensional liquid chromatography (2D-LC) - high resolution mass spectrometry system (HRMS) was developed, expanding the range of the partition coefficient in octanol/water of the residue analysis from -8 to 12. A high-coverage serum residue screening strategy was further designed by integrating 2D-LC system with HRMS full MS/data independent acquisition and automatic spectral library searching. This strategy enables to simultaneously screen 1210 pesticides, veterinary/human drugs, other chemical pollutants and their metabolites in serum with a single analysis. Method validation showed 92% and 81% of 1022 residues spiked in serum could be detected at 50 ng/mL and 5 ng/mL, respectively. The developed method was applied to the analysis of 24 separately pooled serum samples, 58 suspect residues were found, some of them were detected at high frequencies over than 50%. Among them, 4,6-Dinitro-O-cresol and probable carcinogenic folpet are highly toxic, and cimaterol is banned in China. Collectively, this study developed a 2D-LC-HRMS -based screening strategy for screening pesticides, veterinary/human drugs, and other chemical pollutants in serum, it is helpful for studying the effect of exogenous exposures on human health.

Metabolome-wide association study of the relationship between chlorpyrifos exposure and first trimester serum metabolite levels in pregnant Thai farmworkers

Article

Sep 2022
ENVIRON RES

Introduction Organophosphate (OP) insecticides, including chlorpyrifos, have been linked with numerous harmful health effects on maternal and child health. Limited data are available on the biological mechanisms and endogenous pathways underlying the toxicity of chlorpyrifos exposures on pregnancy and birth outcomes. In this study, we measured a urinary chlorpyrifos metabolite and used high-resolution metabolomics (HRM) to identify biological perturbations associated with chlorpyrifos exposure among pregnant women in Thailand, who are disparately exposed to high levels of OP insecticides. Methods This study included 50 participants from the Study of Asian Women and their Offspring's Development and Environmental Exposures (SAWASDEE). We used liquid chromatography-high resolution mass spectrometry to conduct metabolic profiling on first trimester serum samples collected from participants to evaluate metabolic perturbations in relation to chlorpyrifos exposures. We measured 3,5,6-trichloro-2-pyridinol (TCPy), a specific metabolite of chlorpyrifos and chlorpyrifos-methyl, in first trimester urine samples to assess the levels of exposures. Following an untargeted metabolome-wide association study workflow, we used generalized linear models, pathway enrichment analyses, and chemical annotation to identify significant metabolites and pathways associated with urinary TCPy levels. Results In the 50 SAWASDEE participants, the median urinary TCPy level was 4.36 μg TCPy/g creatinine. In total, 691 unique metabolic features were found significantly associated with TCPy levels (p < 0.05) after controlling for confounding factors. Pathway analysis of metabolic features associated with TCPy indicated perturbations in 24 metabolic pathways, most closely linked to the production of reactive oxygen species and cellular damage. These pathways include tryptophan metabolism, fatty acid oxidation and peroxisome metabolism, cytochromes P450 metabolism, glutathione metabolism, and vitamin B3 metabolism. We confirmed the chemical identities of 25 metabolites associated with TCPy levels, including glutathione, cystine, arachidic acid, itaconate, and nicotinamide adenine dinucleotide. Discussion The metabolic perturbations associated with TCPy levels were related to oxidative stress, cellular damage and repair, and systemic inflammation, which could ultimately contribute to health outcomes, including neurodevelopmental deficits in the child. These findings support the future development of sensitive biomarkers to investigate the metabolic underpinnings related to pesticide exposure during pregnancy and to understand its link to adverse outcomes in children.

Basic Principles and Fundamental Aspects of Mass Spectrometry

Chapter

Full-text available

Mar 2022

For both quantitative and qualitative applications, mass spectrometry (MS) has evolved to become an effective analytical instrument. The first mass spectrometer was designed in 1912 and has since progressed from studying only small inorganic molecules to biological macromolecules, with virtually no mass constraints. Research in drug discovery, in general, depends considerably on MS technologies. The capability of mass spectrometry to analyze proteins and other biological materials is due to the advancements made by establishing soft ionization techniques that can turn biological molecules into ions, such as electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI). Consequently, MALDI has the benefit of generating peptide and protein single-charge ions, reducing spectral complexity. Regardless of the cause of ionization, a mass spectrometer's sensitivity is connected to the mass analyzer where ion separation occurs. Both quadrupole and flight time (ToF) mass probes are widely used and can be designed as QToF tandem mass spectrometric instruments combined. As the title suggests, tandem mass spectrometry (MS/MS) is the outcome of conducting two or more concurrent ion separations, typically integrating two or more mass analyzers. The development of high-resolution mass spectrometers resulted in the combination of a quadrupole and flight time Historically, this paper introduces mass spectrometry and describes the benefits and drawbacks of ESI and MALDI along with quadruple and ToF mass analyzers, including scientific mass analyzers. This paper is of an introductory nature and is intended for graduate and senior biochemistry students as well as chemists and biochemists who are not acquainted with mass spectrometry and want to learn the basics; it is not intended for professionals in mass spectrometry. Keywords: Mass spectroscopy, electrospray ionization, matrix-assisted laser desorption ionization, quadrupole, tandem mass spectrometry, proteomics, foodomics.

Mass Spectrometry in Food Authentication

Chapter

Full-text available

Mar 2022

Foodomics has recently emerged as a new discipline that studies food and nutritional products with modern analytical tools, including mass spectrometry (MS), to ensure food quality and safety. Foodomics is currently being used as a powerful tool in food authentication. It has been used to authenticate food items such as cereals, wine, honey, chocolates, and other commercial products. MS is the most suitable technique for authentication of food products because of its precise, accurate, and reproducible analytical power. MS-based techniques are nowadays extensively used for authentication of food and nutritional products. MS-based methods can detect various food components, including nutrients, additives, and toxic contaminants. Due to advancement in separation techniques, ionization and detectors in MS such as liquid chromatography tandem mass spectrometry, gas chromatography mass spectrometry, electrospray ionization tandem mass spectrometry, matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry, surface-enhanced laser desorption/ionization mass spectrometry, desorption electrospray ionization mass spectrometry, direct analysis in real-time mass spectrometry, extractive electrospray ionization mass spectrometry, and tandem-MS approaches have emerged as the method of choice for authentication of food products. This chapter discusses separation techniques and application of MS to analyze food products.

Proteomic Strategies to Evaluate the Impact of Farming Conditions on Food Quality and Safety in Aquaculture Products

Chapter

Full-text available

Mar 2022

Agricultural Pesticide Exposure and Risk Assessment to Human Health in Mexico

Chapter

Full-text available

Nov 2021

In Mexico, pesticides are widely used in agricultural production to control pests, diseases, weeds, and other plant pathogens that allow maintaining good product quality. Occupational exposure to pesticides occurs in the case of agricultural workers in open fields and greenhouses, workers in the pesticide industry, and in domestic use for pest control. Exposure of the population happens mainly through the consumption of food and water contaminated with pesticide residues. Regarding the adverse impacts on the environment and on wildlife, fish, and plants, many of these effects depend on the toxicity of the pesticide, the way it is applied, the weather conditions prevailing during and after application, and its persistence in the environment. All these reasons imply a high risk for exposed populations. For the evaluation of the real levels of pesticide residues in environmental and biological samples, sophisticated analytical methodologies are required, as well as equipment with a high degree of precision and resolution, which allows to detect the compounds of interest unequivocally, which represents a great challenge, given the high costs that this technology represents. A great concern has been manifesting on some part of the Mexican population, who knows about the negative impacts on human health, represented by exposure to certain types of pesticides. For these reasons, this chapter aims to give an overview of the current situation of the type of pesticides that are used in greater proportion in agricultural activity, as well as their levels of concentration.

Ultrasensitive zero-background photoelectrochemical biosensor for analysis of organophosphorus pesticide based on in situ formation of DNA-templated Ag2S photoactive materials

Article

Aug 2021

Herein, a novel signal-on photoelectrochemical (PEC) biosensor with nearly zero background noise (ZBN) was first fabricated to determine the presence of organophosphorus pesticide based on in situ formation of DNA-templated Ag2S photoactive materials, accompanied by hybridization chain reaction (HCR) signal amplification. The capture probe (S1) on the gold nanoparticle-modified electrode can hybridize with the aptamer molecule to generate a simple PEC biosensor. In the presence of a target molecule, the aptamer molecule is released on the double-stranded DNA (dsDNA)-modified PEC biosensor. Meanwhile, the capture probe remains on the electrode and can open the DNA hairpins (H1, H2) which are rich in cytosine, to trigger the HCR reaction. The rich “C” strands are uncovered after formation of a long dsDNA polymer strand, which can assemble multiple silver ions (Ag+) by means of by C–Ag+–C chelation. Then, a large number of Ag2S can be generated by challenging with S2− solution, producing a satisfactory photocurrent signal. The photoactive material is formed in situ, which eliminates the laborious operation. Moreover, the signal can be highly amplified with nearly zero background noise and HCR signal amplification. Under optimal conditions, the ZBN aptasensor exhibited high sensitivity and selectivity, with a low detection limit of 2 pg mL−1 for malathion. Importantly, the sensing platform can also be applied to determine the presence of malathion in real samples.Graphical abstract In this assay, a novel signal-on photoelectrochemical biosensor with nearly zero background noise was first fabricated to determine the presence of organophosphorus pesticide based on in situ formation of DNA-templated Ag2S photoactive materials, accompanied by hybridization chain reaction signal amplification.

Analytical strategies to measure herbicide active ingredients and their metabolites

Chapter

Jan 2021

Almost half the pesticides used in the world are herbicides. Exposure to high levels of herbicides can cause undesirable or toxic effects on nontarget organisms, humans, and the environment. The accurate measurement of herbicides is therefore needed to avoid or assess the risk of exposure. This chapter explains why herbicides have to be accurately measured in food and animal feed and in human matrices. The typical analytical tools and developmental strategies that can be applied in a routine laboratory dealing with risk assessment and human biomonitoring are reviewed. A focus on glyphosate analysis as a typical application in a laboratory analyzing herbicides in fruits and human urine is given at the end of the chapter.

Pesticides and their metabolites in human urine: development of multi-analyte method by LC-MS/MS and GC-MS/MS

Article

Mar 2021

The objective of this study consists of being able to develop a precise, reliable, easy, cheap and quick method to identify and quantify the presence of pesticide metabolites and their parents in human urine. In order to reach our purpose we selected the pesticides and their metabolites with intended uses on permanent crops such as orchards and vineyard. The activity planning started with the identification of the target list carried out by UHPLC-MS/MS and GC-MS/MS, succeeded by several tests oriented to determine the best sample treatment having recourse to instrumental analysis in the range 5–100 ng/mL. Several purifications were also investigated combining different adsorbents (PSA, EMR-lipid and final polish pouch). The use of formic acid during the extraction step has no impact on the recoveries, whereas the PSA adsorbent in the cleanup step negatively affects the results for all investigated metabolites. Any substantial differences were not observed in urine matrix for parent compounds achieving recoveries higher than 80% and RSD less than 20%. The final polish in combination or not with Enhanced Matrix Removal EMR-lipid did not show statistically significant difference in term of trueness and precision for both metabolites and parents, as evaluated by one-way ANOVA. The 3-OH THPI was the most critical compound with not acceptable results for linearity, trueness and precision.

Dispersive liquid-liquid microextraction using a low transition temperature mixture and liquid chromatography-mass spectrometry analysis of pesticides in urine samples

Article

Mar 2021
J CHROMATOGR A

Biomonitoring is a potent tool to control the health risk of people occupationally and non-occupationally exposed. The latest trend in bioanalytical chemistry is to develop quick, cheap, easy, safe and reliable green analytical procedures to analyse a large number of chemicals in easily accessible biomatrices such as urine. In this paper, a new dispersive liquid–liquid microextraction (DLLME) procedure, conceived to treat urine samples and based on the use of a low transition temperature mixture (LTTM), was developed and validated to analyse twenty pesticides commonly used in farm practises. The LTTM was composed by choline chloride and sesamol in molar ratio 1:3 (ChCl:Ses 1:3); its characterization via differential scanning calorimetry identified it as an LTTM and not as a deep eutectic solvent due to the occurrence of a glass transition at -71 °C. The prepared mixture was used as the extraction solvent in the DLLME procedure, while ethyl acetate as the dispersing solvent. The salting out effect (50 mg mL⁻¹ of NaCl in a diluted urine sample) improved the separation phase and the analyte transfer to the extractant. Due to the high ionic strength and despite the density of the LTTM (1.25 g mL⁻¹), the LTTM layer floated on the top of the sample solution after centrifugation. All extracts were analysed by high-performance liquid chromatography coupled to mass spectrometry. After optimization and validation of the whole method, lower limits of quantitation were in the range of 0.02 – 0.76 µg L⁻¹. Extraction recoveries spanned from 50 to 101 % depending on the spike level and analytes. Precision and accuracy ranges were 3-18% and 5-20%, respectively. The extraction procedure was also compared with other methods, showing to be advantageous for rapidity, simplicity, efficiency, and low cost. Finally, urine samples from ten volunteers were effectively analysed using the developed method.

New sample preparation method to analyse 15 specific and non-specific pesticide metabolites in human urine using LC-MS/MS

Article

Jan 2021
J CHROMATOGR B

This study presents a novel sample preparation method for the determination of both specific and non-specific pesticide metabolites in human urine samples. The method combines a deconjugation step with QuEChERS-based method and solid-phase extraction. In total, 15 pesticide metabolites (diethyl phosphate; diethyl thiophosphate; dimethyl phosphate; diethyl thiophosphate; 2,4-dichlorophenoxyacetic acid; 3-phenoxybenzoic acid; 4-fluoro-3-phenoxybenzoic acid; coumaphos; diethyl dithiophosphate; malathion dicarboxylic acid; p-nitrophenol; cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid; 3,5,6-trichloro-2-pyridinol; N,N-diethyl-3-methylbenzamid and 2-isopropyl-4-methyl-6-hydroxypyrimidine) were separated using liquid chromatography coupled to a mass spectrometer and isotope dilution method for quantitation. The method was validated using recovery tests with recoveries generally ranging from 80 to 120 %. Additionally, 20 urine samples collected from South African children were analysed using the presented method. The median levels of pesticide metabolites found in the urine samples ranged from not detected (N,N-diethyl-3-methylbenzamid) to 22.36 µg/g creatinine (dimethyl phosphate). The novel method developed in this study is sensitive, selective, robust and reproducible while also conserving the amount of sample, chemicals, material and time required. Due to the low limits of detection obtained for individual pesticide metabolites, the method is capable of quantifying trace levels of pesticide metabolites in urine, which thus makes it an ideal tool for biomonitoring studies.

Variability of urinary pyrethroid biomarkers in Chinese young-aged men and women over one year

Article

Nov 2020
ENVIRON POLLUT

Pyrethroids are a class of the most commonly used insecticides. The urinary metabolites are usually used as biomarkers of pyrethroid exposures in humans. In this study, the temporal variability of urinary pyrethroid biomarkers was investigated among 114 Chinese young-aged adults who provided up to 4–11 urine samples over one year. The detection rates of four urinary pyrethroid biomarkers, 3-phenoxybenzoic acid (3PBA), 4-fluoro-3-phenoxybenzoic acid (4F-3PBA), trans-2,2-(dichloro)-2-dimethylvinylcyclopropane carboxylic acid (trans-DCCA) and cis-2,2-(dichloro)-2-dimethylvinylcyclopropane carboxylic acid (cis-DCCA) were 100%, 8%, 69% and 44%, respectively. The intraclass correlation coefficient (ICC) estimates for 3PBA indicated poor reproducibility (<0.15) in the spot urine samples of young-aged adults over a week, month and year. Log-transformed 3PBA used the least number of random spot urine samples (≥4) per person, which would provide a reliable biomarker estimate (ICC≥0.40) over a year. As the predictors of the top 33% yearly average 3PBA concentrations, the sensitivity and specificity of 3PBA ranged from 0.25 to 0.89, 0.58 to 0.96, respectively. Based on the results of this study, we recommend at least 4 urine samples collected 3 months apart for prospective assessment of pyrethroid exposure in the epidemiological studies to estimate exposure-response relationships between pyrethroids and health outcomes with relative long-term exposure periods.

In utero pyrethroid pesticide exposure in relation to autism spectrum disorder (ASD) and other neurodevelopmental outcomes at 3 years in the MARBLES longitudinal cohort

Article

Nov 2020

Background We assessed the relationships between prenatal pyrethroid pesticide exposure and autism spectrum disorders (ASD) or non-typical development (non-TD) at 3 years. Methods Participants were mother-child pairs (n=201) in the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) cohort. Because familial recurrence risk is high, MARBLES enrolls pregnant women with a family history of ASD. Children were clinically assessed at 3 years of age and classified into 3 outcome categories: ASD, typically developing (TD), or non-TD (and not meeting criteria for ASD). Repeated maternal second and third trimester urine samples were analyzed for pyrethroid metabolite 3-phenoxybenzoic acid (3-PBA). Multinomial logistic regression was used to obtain relative risk ratios (RRR) linking 3-PBA concentrations averaged across each trimester and over pregnancy with child’s outcome, either ASD or non-TD vs. TD. Models were adjusted for specific gravity, maternal pre-pregnancy BMI, prenatal vitamin use, birth year, home-ownership, and TCPy (3,5,6-trichloro-2-pyridinol) pregnancy concentrations. Results The median specific gravity corrected 3-PBA concentration of all samples was 1.46 ng/ml. Greater second trimester 3-PBA concentrations were associated with modestly elevated relative risk ratios of ASD (RRR: 1.50 (95% CI 0.89 to 2.51), p = 0.12). There were no differences between non-TD and TD. Conclusions This study found no evidence for differences in 3-PBA comparing non-TD with TD. A moderately elevated RRR was found comparing urinary 3-PBA concentrations for ASD versus TD; however, the confidence interval was wide and hence, these findings cannot be considered definitive.

Analytical Methods for Determining Pyrethroid Insecticides in Environmental and Food Matrices

Chapter

Jun 2020

Maria Luisa Feo

In this chapter, an overview of different aspects of current analytical methodologies such as sample preparation, extraction, purification, and instrumental analysis for pyrethroids is discussed. Recent development in sample preparation and extraction is presented. Regarding instrumental analysis, gas chromatography (GC) coupled to electron capture detection or mass spectrometry (MS) including tandem MS is generally preferred for analysis of pyrethroids. Although liquid chromatography has been used as a possible solution to reduce isomerization of pyrethroids that can occur at higher temperature, the advantages and disadvantages of different instrumental techniques are discussed here.

Pesticide metabolite concentrations in Queensland pre-schoolers - Exposure trends related to age and sex using urinary biomarkers

Article

Sep 2019
ENVIRON RES

This study aimed to assess pesticide concentration and composition trends associated with age and sex in Australian infants and toddlers. Individual urine samples (n = 400) were collected in 2014/5 from Queensland infants and toddlers aged 0-5 y and composited into 20 pools of 20 individual samples by age (of 5 strata) and sex. Nineteen biomarkers including organophosphate and pyrethroid pesticide metabolites, herbicides and metabolites, and an insect repellent, DEET, were measured. In total, seven organophosphate pesticide metabolites, three pyrethroid metabolites and one herbicide metabolite were detectable in >50% of the sample pools. A significant increase of concentrations of dimethyl phosphate, dimethyl dithiophosphate, diethyl thiophosphate (DETP), 3,5,6-trichloro-2-pyridinol (TCPY), 4-nitrophenol and 3-phenoxybenzoic acid with age was observed (with the p value of <0.0001 to 0.034). This suggested that exposure increases following weaning or as a result of increased dietary intake and mobility/activity. Significant age trends remained after adjustment for body weight and urine flow for DETP and TCPY (p = 0.029 and 0.016 respectively). The level of estimated "worst-case scenario" daily intake of chlorpyrifos from these pooled samples ranged from 0.40 to 1.8 μg/kg-day, which was below the Australian Acceptable Daily Intake guideline (3 μg/kg-day). This study presents the first dataset of age trends in concentrations of these pesticides for infants and toddlers and contributed to new understanding of exposure pathways and potential risks.

Analytical Methods for Determination Urinary Metabolites of Synthetic Pyrethroids

Chapter

Jan 2020

Insecticides are natural and synthetic chemicals used to kill unwanted pests. However, humans and insect share similar molecular targets, and thus, insecticides are potentially hazardous to human health. Several health effects might be observed in experimental animals following controlled exposure to insecticides. Synthetic pyrethroids are still a relatively novel group of insecticides widely used not only in agriculture but also in human and veterinary medicine, forestry, and public health and for commercial pest control and residential consumer use. They play a unique role in fighting against malaria in tropical areas, where the WHO recommends pyrethroids among others for indoor residual spraying (IRS) and impregnation of bed nets to prevent mosquito biting.

Ingenious Design and Development of recyclable 2D BiOCl Nanotiles Attached Tri-functional Robust Strips for High Performance Selective Electrochemical Sensing, SERS and Heterogenous Dip Catalysis

Article

Dec 2019
CHEM ENG J

This research investigation demonstrates the SPCE catalytic strip in action not only for electrochemistry but also for SERS and catalysis. The fabricated low-cost catalytic strips holds huge potential in realizing industrial demands via eco-friendly manner. In this present work, we have synthesized 2D BiOCl nanotiles (BOC-NT) through hydrothermal procedure and subsequently, we have characterized in detail to understand the crystal architecture, morphology and surface area. Electron microscopy studies reveals a homogeneous 2D morphology without any agglomerations. Through a novel GOD process the SPCE catalytic strips are fabricated. More over this work establishes the first paradigm of SPCE catalytic strips hired for the electrochemical sensing, SERS and the chemicatalysis of Methyl Viologen (MyV), a hazardous herbicide. Upon all the three catalytic investigations, BOC-NT based SPCE catalytic strips performed exceptionally well. In the electrochemical sensing, the strip achieved a remarkable linear range (0.01–1331.1 μM) with detection limit of 0.0073 μM. In addition, the plasmonic SERS strip presented an impressive enhancement factor (EF) of 10⁶ for MyV coupled with the detection limit of 10⁻¹⁰ M. Finally, in the chemicatalysis process our catalytic strip aided in degradation of MyV in 9 min. Further, the possible mechanism for SERS and catalysis is also proposed.

Development of a questionnaire-based insecticide exposure assessment method and comparison with urinary insecticide biomarkers in young Australian children

Article

Jul 2019

Environmental and behavioural factors assessed via an online questionnaire were compared to insecticide metabolite concentrations in urine collected from 61 children from South East Queensland, Australia. Metabolite concentrations (μg/L urine) were transformed using the natural logarithm prior to regression analysis and adjusted for age and creatinine. A significant dietary association was reported for vegetable intake and 3-phenoxybenzoic acid (3-PBA) (β: 1.47 for top quartile of intake versus bottom quartile of intake 95% CI: 0.36, 2.57). Intake of vegetables and fruit were also positively associated with sum non-specific organophosphate metabolites (ƩnsOP). ƩnsOP concentrations were lower when fruits and vegetables were always or almost always washed prior to cooking or eating (β: -0.69 95% CI: -1.25, -0.12). In multivariable modelling 3-PBA concentrations were also associated with hand-washing frequency (β: 1.69 95% CI: 0.76, 2.61 for <1 day versus > 3 day), presence of a dog in the home (β: 0.73 95% CI: 0.07, 1.38), frequency of pest-spray use in the summer months (β: 0.88 95% CI: 0.22, 1.54 weekly versus less than weekly) and season (β: 0.88 95% CI: 0.32, 1.44 for spring/summer versus winter/autumn). This is the first study in Australia to report dietary, behavioural and environmental factors associated with biomarkers of insecticide exposure in young children.

ELECTROSPRAY IONIZATION TANDEM MASS SPECTROMETRY OF PERMETHRINE, HIGHLIGHTING AN ION OF DIBENZOFURYLIUM STRUCTURE

Article

Full-text available

Jun 2019

The present work allowed us to study permethrin behavior in mass spectrometry The mass spectrum is characterized by the presence of an intense pic at m/z=183 leading to identify the presence of permethrin in a mixture. A priviliged fragmentations of ions formed have also been highlighted, showing in particular the formation of an ion with dibenzofurylium structure. Résumé: Le présent travail a permis d'étudier la perméthrine en spectrométrie de masse. Le spectre de masse de cette molécule est caractérisé, en particulier, par la présence d'un pic intense à m/z=183, permettant d'identifier la présence de la perméthrine dans un mélange. Des fragmentations privilégiées de cet ion ont été également expliquées en se basant sur la spectrométrie de masse en tandem. Et mettant en évidence un ion de structure dibenzofurylium.

Simultaneous determination of pyrethroids and their metabolites in human plasma using liquid chromatography tandem mass spectrometry

Article

Jun 2019
FORENSIC SCI INT

Pyrethroids, organic compounds similar to natural pyrethrums, constitute the majority of insecticides. Pyrethroids are widely used around the world owing to their excellent selective toxicity to certain insects. In addition, they are easily found in daily life, accounting for most household pesticides. Owing to the easy access to pyrethroid insecticides, pyrethroid-related accidents and suicides have occurred yearly. For the first time, nine pyrethroids commonly used in South Korea and their seven major metabolites were simultaneously analyzed and validated in human plasma using liquid chromatography triple quadrupole mass spectrometry. Plasmas spiked with these pyrethroids and their metabolites were prepared and deproteinized via the addition of acetonitrile. This deproteinized supernatant was filtered and directly injected to ascertain the liquid chromatography-tandem mass spectrometry. For a sensitive and reproducible analysis, all the pyrethroid and metabolite analysis conditions for the multiple reaction monitoring mode were optimized in advance and employed. The validation parameters of the method, including the specificity, linearity, limit of detection, limit of quantification, accuracy, precision, recovery, matrix effect, and stability were also evaluated. The R2 value of linearity was greater than 0.997 for all the analytes, the accuracy ranged from 81.8% to 112.3%, the precision from 0% to 10.1%, and the recovery from 90.9% to 112.4%, depending on the analyte. The stability was 97.0% to 107.0% in fresh plasma and 97.6% to 107.7% in corrupt plasma. The results were satisfactory for all the validation parameters. Furthermore, authentic pyrethroid-poisoned samples were analyzed using this validation method, to determine the suitability; deltamethrin and its metabolites, cis-DBCA and 3-PBA, were successfully analyzed.

Human Biomonitoring as a Useful Approach to Health Risk Assessment Compared with Occupational Exposure Assessment of Insecticide Intake: Fundamental Study Focused on Local Populations and Occupational Fields: ―地域・職域集団を対象とした基礎的検討―

Article

Full-text available

Jan 2018

Jun Ueyama

Human biomonitoring (HBM) is a technique to evaluate chemical exposure level by measuring the levels of chemicals or related substances such as their metabolites or adducts in biological samples (e.g., urine or blood). Compared with exposure assessment by an approach to estimate insecticide intake from diet or the environment, HBM can provide information more specific to an individual exposure dose and can reflect the exact body burden condition at the time of measurement. If the analytical sensitivities, completeness and cost-effectiveness of the method are improved further, HBM might be widely applicable to not only research fields such as epidemiological and occupational study but also routine analysis for effective prevention of the exposure of the human body to chemical substances. In this article, we provide an overview of HBM as a determination method for insecticide exposure markers in urine and its applications, and discuss future research perspectives in the field of environmental and occupational health.

A sensitive and efficient procedure for the high-throughput determination of nine urinary metabolites of pyrethroids by GC-MS/MS and its application in a sample of Japanese children

Article

Jul 2018

Four pyrethroids (PYRs), metofluthrin, profluthrin, tefluthrin, and transfluthrin, which were newly developed and have relatively high vapor activity at ambient temperature, are now playing a key role in safely controlling insects in our daily lives. We developed a sensitive and high-throughput determination method for urinary metabolites derived from the newly developed PYR, e.g., 2,3,5,6-tetrafluoro-1,4-benzenedimethanol (HOCH2-FB-Al), 2,3,5,6-tetrafluorobenzyl alcohol (FB-Al), and other PYR metabolites such as trans-chrysanthemumdicarboxylic acid (trans-CDCA) and 3-phenoxybenzoic acid (3PBA). After high temperature acid hydrolysis of 2 mL urine sample in 24-deep well plate, the PYR metabolites were extracted by semi-automated liquid-liquid extraction with tert-butyl methyl ether. N,O-Bis (trimethylsilyl) trifluoroacetamide containing 1% trimethylchlorosilane or 1,1,1,3,3,3-hexafluoroisopropanol were used for the derivatization of PYR metabolites, and the derivatized metabolites were analyzed separately by GC-MS/MS equipped with dual injector system (DB-5MS and mid- to high-polarity phase Rtx-65 columns). The derivatization and evaporation conditions were mainly optimized for improving sensitivity and reproducibility. The mean within-run day precisions were less than 18.4% (relative standard deviation, %RSD) with low detection limits ranging from 0.01 μg/L for HOCH2-FB-Al to 0.06 μg/L for trans-CDCA. This method was successfully applied to urine samples obtained from 50 3-year-old children with high detection frequencies (e.g., 82% for HOCH2-FB-Al and 84% for FB-Al). This method may be a pivotal tool for developing risk assessment from PYR exposure in the general population.

Variability of urinary pesticide metabolite concentrations during pregnancy in the MARBLES Study

Article

May 2018
ENVIRON RES

Background: Variability of short-lived urinary pesticide metabolites during pregnancy raises challenges for exposure assessment. Objectives: For urinary metabolite concentrations 3-phenoxybenzoic acid (3-PBA) and 3,5,6-trichloro-2-pyridinol (TCPy), we assessed: (1) temporal variability; (2) variation of two urine specimens within a trimester; (3) reliability for pesticide concentrations from a single urine specimen to classify participants into exposure tertiles; and (4) seasonal or year variations. Methods: Pregnant mothers (N = 166) in the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) Study provided urine specimens (n = 528). First morning void (FMV), pooled, and 24-h specimens were analyzed for 3-PBA and TCPy. For 9 mothers (n = 88 specimens), each urine specimen was analyzed separately (not pooled) to estimate within- and between-person variance components expressed as intraclass correlation coefficients (ICC). Pesticide concentrations from two specimens within a trimester were also assessed using ICC's. Agreement for exposure classifications was assessed with weighted Cohen's kappa statistics. Longitudinal mixed effect models were used to assess seasonal or year variations. Results: Urinary pesticide metabolites were detected in ≥ 93% of specimens analyzed. The highest ICC from repeated individual specimens was from specific gravity-corrected FMV specimens for 3-PBA (ICC=0.13). Despite high within-person variability, the median concentrations did not differ across trimesters. Concentrations from pooled specimens had substantial agreement predicting exposure categories for TCPy (K = 0.67, 95% CI (0.59, 0.76)) and moderate agreement for 3-PBA (K = 0.59, 95% CI (0.49, 0.69)). TCPy concentrations significantly decreased from 2007 to 2014. Conclusions: Pooled specimens may improve exposure classification and reduce laboratory costs for compounds with short biological half-lives in epidemiological studies.

Analytical Methods for the Determination of Urinary 2,4-Dichlorophenoxyacetic Acid and 2-Methyl-4-Chlorophenoxyacetic Acid in Occupationally Exposed Subjects and in the General Population

Article

Full-text available

Jul 1997

Two methods for the quantitative analysis of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) in urine were compared. The first was an high-performance liquid chromatography method using a C8 column with ion suppression and diode array detection. The urine extracts were first purified by solid-phase extraction (SPE) on silica capillary columns. The detection limit of the method was 15 micrograms/L for both compounds. The percentage coefficient of variation of the whole analysis evaluated at a concentration of 125.0 micrograms/L was 6.2% for 2,4-D and 6.8% for MCPA. The mean recovery of analysis was 81% for 2,4-D and 85% for MCPA. The second was a gas chromatographic (GC) method in which the compounds were first derivatized with pentafluorobenzylbromide to pentafluorobenzyl esters, which were determined with a slightly polar capillary column and electron capture detection. Before GC analysis, the urine extracts were purified by SPE on silica capillary columns. This method had a detection limit of 1 microgram/L for both compounds and a percentage coefficient of variation of the whole analysis, evaluated at a concentration of 30.0 micrograms/L, of 8% for 2,4-D, and of 5.5% for MCPA. the mean recovery was 87% for 2,4-D and 94% for MCPA. The low detection limit made the second method suitable for assaying the two herbicides in the general population. Duplicate analysis of ten urine samples from occupationally exposed subjects by the two methods gave identical results for a wide range of concentrations.

A Rapid, Sensitive Method for the Quantitation of N-Acetyl-S-(2-Hydroxyethyl)-l-Cysteine in Human Urine Using Isotope-Dilution HPLC-MS-MS

Article

Full-text available

Mar 1998

Because of increasing concern about exposure to carcinogens and other toxicants, reliable methods for biological monitoring of potentially exposed populations must be developed. For biological monitoring to be useful, appropriate biomarkers of exposures to xenobiotics must be identified, and sensitive, specific methods for quantifying the targeted biomarker must be developed. We have developed a sensitive and selective method for the analysis of N-acetyl-S-(2-hydroxyethyl)-L-cysteine (HEMA), urinary metabolite of at least three different known human carcinogens (vinyl chloride, ethylene oxide, and ethylene dibromide). The method uses strong anion-exchange solid-phase extraction and isotope-dilution high-performance liquid chromatography-tandem mass spectrometry. Our method is simple and is not labor intensive; the preparation time per sample is less than 10 min. Because urine samples vary in both their concentration and ion strength, intersample variability in HEMA recovery during the extraction is large. To overcome this inherent limitation, we use the isotope-dilution technique, which allows a complete correction for the extraction recovery for each sample. The limit of detection of the method is 0.68 microgram/L in a 1-mL urine sample with a coefficient of variation of 22% (determined by replicate analyses at both 4 and 11 micrograms/L) and an accuracy indistinguishable from 100%. Preliminary analyses of urine from a population with no known overt exposure to the parent toxicants show a frequency of detection of approximately 75%, which indicates that this method has the sensitivity to detect urinary HEMA derived from environmental exposure. We are currently using this method to establish a reference range of background exposure to these toxicants in the U.S. population.

Quantitation of Dialkyl Phosphate Metabolites of Organophosphate Pesticides in Human Urine Using GC-MS-MS with Isotopic Internal Standards

Article

Full-text available

Jul 2002

Human exposure to organophosphate pesticides can be estimated from the presence of urinary metabolites. An isotope-dilution gas chromatography-tandem mass spectrometry (GC-MS-MS) method was developed for quantitating the six dialkyl phosphate urinary metabolites of at least 29 organophosphate pesticides. Urine samples were spiked with stable isotope analogues of the dialkyl phosphates, evaporated using azeotropic distillation, followed by chemical derivatization of the metabolites to their respective chloropropyl phosphate esters. The chloropropyl phosphate esters were concentrated and then analyzed using GC-MS-MS. The limits of detection (LODs) of the method were in the low-to-mid picogram-per-milliliter range (parts per trillion) with coefficients of variation of less than 20%. The use of stable isotope analogues as internal standards for each of these metabolites allows for the highest degree of accuracy and precision. Additionally, the low LODs allow the use of this method in general population studies.

Identification and gas chromatographic determination of some carboxylic acid metabolites of N,N-diethyl-m-toluamide in rat urine

Article

Jun 1990

Adult Wistar rats dosed intraperitoneally and topically (50 mg/kg) with N,N-diethyl-m-toluamide (1) excreted m-[(diethylamino)carbonyl]benzoic acid (3), m-[(ethylamino)carbonyl]benzoic acid (6), m-(aminocarbonyl)benzoic acid (9), and m-toluic acid (10) in their urine. These carboxylic acids were isolated by extraction of acidified urine samples with ethyl acetate and were detected as their methyl esters by GC and GC-MS. A quantitative analytical procedure, based on GC with a nitrogen-phosphorus detector, a capillary column of DB-1, and an internal standard of m-[(dipropylamino)carbonyl]benzoic acid (13), was developed to determine 3 and 6 in urine samples from treated rats. After 24 h, these major metabolites together accounted for 77% and 82% of the intraperitoneally administered dose in separate experiments with four male rats per experiment. In trials with 1 applied topically, 3 and 6 collectively represented 47% (males) and 49% (females) of the dose in 0-48-h urine collections. In the topical experiments, 5-6% of 1 was excreted unchanged.

Determination of trace levels of pyrethroid metabolites in human urine by capillary gas chromatography-high resolution mass spectrometry with negative chemical ionization

Article

Sep 1997

Applications of high-resolution gas chromatography and high-resolution mass spectrometry (GC-MS) for identification and quantitation of trace amounts of pyrethroid metabolites in human urine samples are demonstrated. The method covers the pyrethroid metabolitescis- andtrans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropane carboxylic acid (cis- andtrans-DCCA),cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (cis-DBCA), 4-fluoro-3-phenoxybenzoic acid (FPBA), and 3-phenoxybenzoic acid (3-PBA). After acid-induced hydrolysis of urine samples and exhaustive solvent extraction, a carbodiimide-coupled esterification of the free carboxylic acids with hexafluoroisopropanol (HFIP) is applied. Identification of the derivatives formed is achieved by low-resolution electron-impact mass spectrometry (EIMS) using an ion-trap detector. Quantitation was by capillary gas chromatography—high-resolution mass spectrometry using negative chemical ionization (GC-NCIMS). 2-Phenoxybenzoic acid (2-PBA) served as internal standard. The limits of detection forcis- andtrans-DCCA,cis-DBCA, FPBA and 3-PBA were 0.03 μg L−1 or below. The applicability of the presented method was tested on urine samples of persons exposed to low levels of pyrethroids.

The influence of citrate and phosphate on the Mancini single radial immunodiffusion technique and suggested improvements of the determination of urinary albumin

Article

Jan 1979
CLIN CHIM ACTA

When adapting the immediate bromcresol green method for urinary albumin determination a correlation study with the Mancini single radial immunodiffusion (SRID) method was performed. This study showed large disparities between the two methods, SRID giving the higher results. The unsuitability of the currently used SRID methods is demonstrated and improvements to the method are suggested. Known amounts of albumin were added to urine samples as well as to a "synthetic urine", both giving falsely elevated results with the SRID method. On investigating the different components of the "synthetic urine", it was found that the disparities were due to the influence of citrate and phosphate. On addition of citric acid or phosphate to the dilution buffer and/or the gel buffer, the results of the SRID method agreed with those of other methods and with the expected values. The findings presented in this paper can probably be extended to other immunological methods too since it seems to be the antigen-antibody reaction which is affected.

Tissue residue and comparative metabolism studies on tiazuril in the chicken, rat, dog, and monkey

Article

Nov 1977

The metabolism of the anticoccidial compound tiazuril (2-[3,5-dimethyl-4-(4-chlorophenylthio)-phenyl]-as-triazine-3,5(2H,4H)-dione) was studied in the chicken and laboratory animals. Following oral administration of tritium-labeled tiazuril (3H-T) to the chicken at 1 mg/kg, 3H-T equivalents of radioactivity was 0.06 ppm or less in edible tissues and plasma 5 days after dosing. Throughout the withdrawal period, radioactivity was higher in plasma, liver, and kidney than muscle, skin, and fat. Tiazuril (T) is metabolized by oxidation of the sulfur atom to T-SO and T-SO2 and by hydroxylation of the chlorophenyl ring to HO-T, HO-T-SO, and HO-T-SO2. T-SO2 and HO-T-SO are the major metabolites in liver and excreta, respectively. Broilers maintained on T in feed at 0.0015% for 8 weeks showed less than 0.01 ppm of T and 0.03 ppm or less of T-SO2 in plasma and edible tissues 4 days after drug withdrawal. In comparative metabolism studies, the dog is distinguished from the chicken, rat, and monkey by maintaining persistent concentrations of T in plasma and by its inability to hydroxylate the drug or its sulfoxidation products.

High-performance liquid chromatography of pirimiphos methyl and five metabolites

Article

Feb 1979
J CHROMATOGR A

Pirimiphos methyl is an organophosphorus insecticide which is rapidly metabolised by plants and animals to several modified triesters and free hydroxyprimidines. A method is described for the determination by reversed-phase high-performance liquid chromatography of pirimiphos methyl and its five major metabolites in plasma and urine. Separations were performed by isocratic and gradient elutions from short columns packed with SAS-Hypersil, a relatively new column packing.

Malathion exposure studies. Determination of mono- and dicarboxylic acids and alkyl phosphates in urine

Article

Nov 1977

A method for the analysis of the dialkyl phosphate metabolites of organophosphorus pesticides was modified to permit analysis of the monocarboxylic acid (MCA) and dicarboxylic acid (DCA) metabolites of malathion. Recoveries of MCA and DCA from spiked urine are presented, as well as the results of analyses of urine from rats exposed to malathion at five levels. Data from both exposed and unexposed humans are presented.

The metabolism of cypermethrin in man: Differences in urinary metabolite profiles following oral and dermal administration

Article

Sep 1992

1. The pyrethroid insecticide cypermethrin was administered orally to six male volunteers as a single dose of 3.3 mg (cis: trans 1:1) and dermally to six volunteers at a dose of 31 mg/800 cm2 (cis:trans 56:44) as a soya oil-based formulation. Urine samples were collected for up to 5 days and analysed for the metabolites cis and trans 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCVA), 3-phenoxybenzoic acid (3PBA) and 3-(4'-hydroxyphenoxy) benzoic acid (4OH3PBA) following an acid hydrolysis procedure. 2. Following oral dosing approx. equal amounts of (cis+trans DCVA) and (3PBA+4OH3PBA) were excreted with peak excretion rates occurring between 8 and 24 h after dosing. The ratio of trans:cis DCVA was on average 2:1. Based on DCVA measurements the amount of cypermethrin absorbed was estimated to be between 27% and 57% (mean 36%) of the administered dose. 3. Peak urinary excretion rates of metabolites occurred between 12 and 36 h after dermal dosing. The amount of metabolites derived from the phenoxybenzyl moiety (3PBA+4OH3PBA) was on average 4 times greater than the amount of (cis+trans DCVA) recovered in urine. The ratio of trans:cis DCVA was, on average 1:1.2. Based on the recovery of the phenoxybenzyl metabolites it is estimated that 0.85-1.8% (mean 1.2%) of the administered cypermethrin was absorbed. 4. These studies demonstrate marked differences in the urinary metabolite profile by the two routes, and provide an improved basis for determining the extent and main route of absorption of cypermethrin under occupational exposure conditions.

Chlorpyrifos: Pharmacokinetics in human volunteers*1

Article

Apr 1984

The kinetics of chlorpyrifos, an organophosphorothioate insecticide, and its principal metabolite, 3,5,6-trichloro-2-pyridinol (3,5,6-TCP), were investigated in six healthy male volunteers given a single 0.5 mg/kg po and, 2 or more weeks later, a 0.5 or 5.0 mg/kg dermal dose of chlorpyrifos. No signs or symptoms of toxicity or changes in erythrocyte cholinesterase were observed. Plasma cholinesterase was depressed to 15% of predose levels by the 0.5 mg/kg po dose but was essentially unchanged following the 5.0 mg/kg dermal dose. Blood chlorpyrifos concentrations were extremely low (less than 30 ng/ml), and no unchanged chlorpyrifos was found in the urine following either route of administration. Mean blood 3,5,6-TCP concentrations peaked at 0.93 micrograms/ml 6 hr after ingestion of the oral dose and at 0.063 micrograms/ml 24 hr after the 5.0 mg/kg dermal dose. 3,5,6-TCP was cleared from the blood and eliminated in the urine with a half-life of 27 hr following both the po and dermal doses. An average of 70% of the po dose but less than 3% of the dermal dose was excreted in the urine as 3,5,6-TCP; thus only a small fraction of the dermally applied chlorpyrifos was absorbed. Chlorpyrifos and its principal metabolite were rapidly eliminated and therefore have a low potential to accumulate in man on repeated exposures. Based on these data, blood and/or urinary 3,5,6-TCP concentrations could be used to quantify the amount of chlorpyrifos absorbed under actual use conditions.

Human dose-excretion studies with the pyrethroid insecticide, cypermethrin

Article

Mar 1983

1. An analytical method for monitoring human exposure to cypermethrin has been developed, based on the detection of the free and conjugated forms of the urinary metabolite, the cyclopropanecarboxylic acid. 2. Four male subjects were given a single oral dose, ranging from 0.25 mg to 1.5 mg, of a 1:1 cis/trans mixture of cypermethrin, and urine was monitored for the free and conjugated cyclopropanecarboxylic acid. Urinary excretion of the individual metabolites (cis and trans isomers) was similar for the different dosages. Subjects excreted, on average, 78% of the trans isomer dose, and 49% of the cis isomer dose respectively in 24 h. 3. Thus, as in other mammals, ester cleavage and elimination of the cis and trans cyclopropanecarboxylic acid moieties in the free and conjugated form is a major route of metabolism of cypermethrin in man.

Total and conjugated urinary paranitrophenol after an acute parathion ingestion

Article

Jul 1995
SCI JUSTICE

In a fatal case of acute parathion ingestion, paranitrophenyl sulphate, the paranitrophenyl glucuronide and free paranitrophenol excretion on day 3 were quantitated using a HPLC reverse method with a C18 column following sample preparation using a C18 mini-column and methanol elution. Paranitrophenyl sulphate amounted to about 81% of the total conjugates excreted. The results were confirmed by collecting the fractions identified by high-performance liquid chromatography, hydrolysing them with concentrated hydrochloric acid and quantitating paranitrophenol by gas chromatography. Total paranitrophenol excretion was also determined. The excreted paranitrophenol was equivalent to 76 mg parathion (lethal dose in humans between 20 and 100 mg). No changes in the concentrations of paranitrophenol or its conjugates were seen in the urine on storage, frozen over a one year period.

Determination of Atrazine Metabolites in Human Urine: Development of a Biomarker of Exposure

Article

Jan 1993

Enzyme-linked immunosorbent assays (ELISAs) are reported for the detection of atrazine and its principle metabolite in human urine. The ELISAs can be used with crude urine or following extraction and partial purification by methods described in this report. GC, MS, and HPLC techniques were used to confirm and complement the ELISA methods for qualitative and quantitative detection of urinary metabolites. A series of samples from workers applying this herbicide confirmed a mercapturic acid conjugate of atrazine as a major urinary metabolite. The mercapturate was found in concentrations at least 10 times that of any of the N-dealkylated products or the parent compound. Atrazine mercapturic acid was isolated from urine using affinity extraction based upon a polyclonal antibody for hydroxy-s-triazines and yielded products sufficiently pure for structure confirmation by MS/MS. In a pilot study monitoring applicators, a relationship between cumulative dermal and inhalation exposure and total amount of atrazine equivalents excreted over a 10-day period was observed. On the basis of these data, we propose that an ELISA for the mercapturate of atrazine could be developed as a useful marker of exposure.

Identification of a Major Human Urinary Metabolite of Alachlor by LC-MS/MS

Article

Jul 1996

Identification of a Major Human Urinary Metabolite of Metolachlor by LC-MS/MS

Article

Jul 1997

Analytical method for the determination of urinary 3-phenoxybenzoic acid in subjects occupationally exposed to pyrethroid insecticides

Article

Sep 1997
J Chrom B Biomed Sci Appl

The determination of urinary 3-phenoxybenzoic acid enables exposure to pyrethroid insecticides to be evaluated. A method for the quantitative determination of this metabolite in urine is described. The compound and the internal standard (2-phenoxybenzoic acid) are derivatized with pentafluorobenzylbromide and transformed into pentafluorobenzyl esters, which are determined by gas chromatography with an intermediate polarity capillary column and an electron-capture detector. Before GC analysis, the urinary extracts are purified on LC-Si SPE columns. The proposed method has a detection limit of 0.5 microg/l and a mean recovery of 91.3%. The coefficient of variation of the analytical procedure, evaluated at a concentration of 24.96 microg/l, was 9.58%. Storage of the urine samples for 3 months at -18 degrees C did not lead to significant changes in the concentration of analyte. The method was tested analysing the urine of a farm worker with symptoms of pyrethroid poisoning, occupationally exposed to esfenvalerate.

Determination of metabolites of pyrethroids in human urine using solid-phase extraction and gas chromatography mass spectrometry

Article

Sep 1997
J Chrom B Biomed Sci Appl

The described method permits the determination of the five most important metabolites of the pyrethroids permethrin, cypermethrin, deltamethrin, lambda-cyhalothrin, fenvalerate, phenothrin and beta-cyfluthrin in human urine in one run. The major urinary metabolites of these substances are cis-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (cis-Cl2CA), trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (trans-Cl2CA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (Br2CA), fluoro-3-phenoxybenzoic acid (F-PBA) and 3-phenoxybenzoic acid (3-PBA). After acidic hydrolysis to release the conjugated carboxylic acid metabolites, the analytes were separated from the matrix by means of solid-phase extraction using a reversed-phase column. The components of the eluate were converted to their methyl esters and extracted in hexane. Separation and quantitative analysis of the pyrethroid metabolites was carried out by capillary gas chromatography and mass selective detection. 2-Phenoxybenzoic acid served as an internal standard. The detection limits lay between 0.3 and 0.5 microg per litre urine. The relative standard deviations of the within-series imprecision were between 1% and 6%. The relative recovery rates ranged between 90% and 98%. Using this method we determined the elimination of pyrethroid metabolites in 24-h urine samples from eight pest controllers after indoor application of permethrin. The detected concentrations ranged from 1 to 70 microg g(-1) creatinine.

Applicability of Aspecific Noninvasive Methods for Biomonitoring of Occupational Exposure to Deltamethrin: Preliminary Study Using an Animal Model

Article

Nov 1997

Deltamethrin (CAS registry No. 52918-63-5), a synthetic dibromo-pyrethroid insecticide is highly effective against a broad spectrum of insects, and is widely used on crops and in public health programs. Data on the genotoxicity and carcinogenicity of deltamethrin are rather controversial, depending on the genetic system or the assay used. The aim of the present study was to analyze previously demonstrated metabolic changes using aspecific noninvasive methods in rats which are potentially applicable for monitoring occupational exposure. Since human exposure to pesticides occurs not only to active principles but to all chemicals present in a commercial formulation, we tested both the pure compound and a deltamethrin-based commercial formulation. Groups of rats were treated, i.p., consecutively for 7 days. The daily doses tested were 5 and 10 mg/kg body weight for pure deltamethrin, corresponding to volumes of 178.57 and 377.14 microliter/kg body weight for the commercial formulation (containing 2.8% deltamethrin). Urine was analyzed for mutagenic metabolites, thioethers, and D-glucaric acid content. Faeces extracts were tested for mutagenicity. Results show that DGA urinary excretion values did not mirror the phase I enzyme induction capability of the insecticide. Results obtained for urinary thioethers do not agree completely with those obtained on the influence of deltamethrin on glutathione S-transferase activity in rat liver. In fact, after administration of the deltamethrin commercial formulation, highest thioether excretion values were obtained during the treatment time for treated animals, as compared to controls. The mean values (+/-SEM) of thioether excretion were 0. 033 +/- 0.002 micromole -SH/24 h for control animals, 0.122 +/- 0. 004 and 0.185 +/- 0.025 for the two treatment groups. Thence, thioether determination in urine samples seems to be a suitable aspecific noninvasive method for assessing exposure to deltamethrin-based formulations, particularly those containing xylene and mesitylene as solvents, as in the tested formulation. Negative or toxic results obtained in the urinary and faecal mutagenicity test seem to exclude the formation and excretion of mutagenic metabolites following treatment with deltamethrin.

Human dose-excretion studies with the pyrethroid insecticide cyfluthrin: Urinary metabolite profile following inhalation

Article

Jan 1998

1. Nine male volunteers were exposed to the pyrethroid insecticide cyfluthrin. The study was performed in an exposure room, where an aerosol containing cyfluthrin was sprayed to obtain atmospheres with mean cyfluthrin concentrations of 160 and 40 micrograms/m3. Four volunteers were exposed for 10, 30 and 60 min at 160 micrograms/m3 and another five volunteers were exposed for 60 min at 40 micrograms/m3. For 160 micrograms/m3 exposure urine samples were collected before and immediately after exposure as well as for the periods 1-2, 2-3, 3-4, 4-5, 5-6, 6-12 and 12-24 h after exposure. For 40 micrograms/m3 exposure urine samples were collected before and 2 h after exposure. 2. The main urinary cyfluthrin metabolites, cis-/trans-3-(2,2-dichlorovinyl)-2,2-dimethylycyclopropane carboxylic acid (DCCA) and 4-fluoro-3-phenoxybenzoic acid (FPBA), were determined. The limit of detection (LOD) for all metabolites was 0.0025 microgram in an urine sample of 5 ml (0.5 microgram/l). After inhalative exposure of 40 micrograms cyfluthrin/m3 air for 60 min, the amount of metabolites in urine collected in the first 2 h after exposure was less than the LOD, namely 0.14 microgram for cis-DCCA, 0.15-0.28 microgram for trans-DCCA and 0.12-0.23 microgram for FPBA. 3. Of the metabolites, 93% was excreted within the first 24 h (peak excretion rates between 0.5 and 3 h) after inhalative exposure of 160 micrograms/m3. The mean half-lives were 6.9 h for cis-DCCA, 6.2 h for trans-DCCA and 5.3 h for FPBA. 4. The mean trans-:cis-DCCA ratio was 1.9 for the time course as well as for each subject. 5. The amount of metabolites in urine depends on the applied dose, on the exposure time and shows interindividual differences.

HPLC−Accelerator MS Measurement of Atrazine Metabolites in Human Urine after Dermal Exposure

Article

Aug 1999

Metabolites of atrazine were measured in human urine after dermal exposure using HPLC to separate and identify metabolites and accelerator mass spectrometry (AMS) to quantify them. Ring-labeled [14C]atrazine was applied for 24 h with a dermal patch to human volunteers at low (0.167 mg, 6.45 muCi) and high (1.98 mg, 24.7 muCi) doses. Urine was collected for 7 days. The urine was centrifuged to remove solids, and the supernatant was measured by liquid scintillation counting prior to injection on the HPLC to ensure that < 0.17 Bq (4.5 pCi) was injected on the column. A reversed-phase gradient of 0.1% acetic acid in water and 0.1% acetic acid in acetonitrile became less polar with increasing time and separated the parent compound and major atrazine metabolites over 31 min on an octadecylsilane column. Peaks were identified by coelution with known standards. Elution fractions were collected in 1-min increments; half of each fraction was analyzed by AMS to obtain limits of quantitation of 14 amol. Mercapturate metabolites of atrazine and dealkylated atrazine dominated the early metabolic time points, accounting for approximately 90% of the 14C in the urine. No parent compound was detected. The excreted atrazine metabolites became more polar with increasing time, and an unidentified polar metabolite that was present in all samples became as prevalent as any of the known ring metabolites several days after the dose was delivered. Knowledge of metabolite dynamics is crucial to developing useful assays for monitoring atrazine exposure in agricultural workers.

Direct determination of chlorpyrifos and its main metabolite 3,5,6-trichloro-2-pyridinol in human serum and urine by coupled-column liquid chromatography/electrospray-tandem mass spectrometry

Article

Aug 2000

A rapid and sensitive automated coupled-column liquid chromatography/electrospray tandem mass spectrometry (LC/LC/ES-MS/MS) method has been developed for the quantitation of chlorpyrifos and 3,5,6-trichloro-2-pyridinol (TCP) in both human serum and urine. Human serum was first protein precipitated with acetonitrile, while urine was directly injected into the coupled-column system. A 10 µL aliquot was then analyzed using as first separation column a Discovery C18 5 µm 50 × 2.1 mm; the fraction containing the analyte was transferred on-line to the second column consisting of a ABZ+ 5 µm 100 × 2.1 mm, which was connected to the electrospray source (Z-spray) of a Quattro LC triple-quadrupole instrument. Chlorpyrifos was detected in positive ion mode using four multi reaction monitoring (MRM) transitions while TCP was measured in negative ion mode using three pseudo-MRM transitions. The clean-up performed by the coupled-column approach avoids the use of an internal standard for the correct quantitation of both analytes, and the highly automated procedure renders a sample throughput of more than 100 samples per day. Both compounds can be determined using the same set-up, the only difference in the procedure being the composition of the first mobile phase.

Metabolites of Pyrethroid Insecticides in Urine Specimens: Current Exposure in an Urban Population in Germany

Article

Apr 2001

Pyrethroids are important insecticides used in agriculture, forestry, horticulture, and in the home. In humans, they are rapidly metabolized and renally eliminated. In numerous studies, pyrethroid metabolites have been detected in urine after occupational exposure to insecticides. In this study, we used a new, reliable, easy, and sensitive analytical method to assess the internal pyrethroid exposure of an urban population without exposure to pyrethoids at home or at work (children and adults). A total of 1,177 persons took part in this investigation, including 331 children under 6 years of age and 247 children between 6 and 12 years of age. None of them reported exposure to pyrethroids at home or at work. Accordingly, the levels of permethrin found in household dust from their homes were lower than expected (median < limit of detection; 95th percentile, 4.8 mg/kg; maximum value, 19 mg/kg). Urine specimens were analyzed for cis-3-(2,2-dibromo-vinyl)-2,2-dimethylcyclo-propanecarboxylic acid (Br(2)CA), cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-carboxylic acid (cis-Cl(2)CA and trans-Cl(2)CA), and 4-fluoro-3-phenoxybenzoic acid (F-PBA) using a gas chromatographic method with mass-selective detection. The limit of detection for pyrethroid metabolites was between 0.1 and 0.2 microg/L. trans-Cl(2)CA was detected in 65% of the urine specimens tested, cis-Cl(2)CA was detected in 30%, and Br(2)CA and F-PBA were found in 19% and 16%, respectively, of the urine specimens. The urinary metabolite levels in children did not differ from those in adults, and there was no correlation between the levels of metabolites and indoor exposure to permethrin in household dust. Moreover, no seasonal correlations could be found. The 95th percentile levels in urine specimens were as follows: Br(2)CA, 0.30 microg/L; cis-Cl(2)CA, 0.51 microg/L; trans-Cl(2)CA, 1.43 microg/L; F-PBA, 0.27 microg/L. Background exposure to pyrethroids was found in the general population; it seems to be caused by the uptake of pyrethroids with the diet. This hypothesis needs to be tested in duplicate diet studies combined with biomonitoring. As long as representative data are lacking, however, the rounded 95th percentile values obtained in our study may be used as reference values for pyrethroid metabolites in urine samples from the population in Germany; 95th percentile values for children and adults are as follows: Br(2)CA, 0.3 microg/L; cis-Cl(2)CA, 0.5 microg/L; trans-Cl(2)CA, 1.5 microg/L; and F-PBA, 0.3 microg/L.

Study of matrix effects on the direct trace analysis of acidic pesticides in water using various liquid chromatographic modes coupled to tandem mass spectrometric detection

Article

Sep 2001
J CHROMATOGR A

This study investigated the effects of matrix interferences on the analytical performance of a triple quadrupole mass spectrometric (MS-MS) detector coupled to various reversed-phase liquid chromatographic (LC) modes for the on-line determination of various types of acidic herbicides in water using external calibration for quantification of the analytes tested at a level of 0.4 microg/l. The LC modes included (i) a single-column configuration (LC), (ii) precolumn switching (PC-LC) and (iii) coupled-column LC (LC-LC). As regards detection, electrospray (ESI) and atmospheric pressure chemical ionization (APCI) in both positive (PI) and negative (NI) ionization modes were examined. Salinity and dissolved organic carbon (DOC) were selected as interferences to study matrix effects in this type of analysis. Therefore, Milli-Q and tap water samples both fortified with 12 mg/l DOC and spiked with sulfometuron-methyl, bentazone, bromoxynil, 2-methyl-4-chlorophenoxyacetic acid, and 2-methyl-4-chlorophenoxypropionic acid at a level of about 0.4 microg/l were analyzed with the various LC-MS approaches. Direct sample injection was performed with volumes of 0.25 ml or 2.0 ml on a column of 2.1 mm I.D. or 4.6 mm I.D. for the ESI and APCI modes, respectively. The recovery data were used to compare and evaluate the analytical performance of the various LC approaches. As regards matrix effects, the salinity provided a dramatic decrease in response for early eluting analytes (k value of about 1) when using the LC mode. Both PC-LC and LC-LC efficiently eliminated this problem. The high DOC content hardly effected the responses of analytes in the ESI mode, while in most cases the responses increased when using APCI-MS-MS detection. Of all the tested configurations, LC-LC-ESI-MS-MS with the column combination Discovery C18/ABZ+ was the most favorable as regards elimination of matrix effects and provided reliable quantification of all compounds using external calibration at the tested low level. The major observed effects were verified with statistical evaluation of the data employing backwards ordinary least-square regression. All tested column-switching modes hyphenated to ESI- or APCI-MS-MS allowed the on-line multi-residue analysis of acidic pesticides in the reference water down to a level of 0.1 microg/l in less than 10 min, emphasizing the feasibility of such an approach in this field of analysis.

Different quantitation approaches for xenobiotics in human urine by liquid chromatography/electrospray tandem mass spectrometry

Article

Feb 2002

The potential of liquid chromatography combined with tandem mass spectrometry (LC/MS/MS) for the determination of pesticide metabolites in human urine at the sub‐ppb level is explored. Metabolites from two organophosphorous pesticides, 4‐nitrophenol (from parathion and parathion‐methyl) and 3‐methyl‐4‐nitrophenol (from fenitrothion), are taken as model analytes to conduct this study. After direct injection of the urine sample (10 µL), different approaches were evaluated in order to achieve correct quantitation of analytes using an electrospray ionisation (ESI) interface. Thus, the feasibility of using external calibration was checked versus the use of different isotope‐labeled internal standards. The advantages of applying coupled‐column liquid chromatography (LC/LC) as an efficient clean‐up without any type of sample manipulation are also discussed. The combination of LC/LC with ESI‐MS/MS allows the direct analysis of free metabolites in urine, as the automated clean‐up performed by the coupled‐column technique is sufficient for the removal of interferences that suppress the ionisation of analytes in the ESI source. Using this procedure with external calibration, good precision and recoveries, and detection limits below 1 ng/mL are reached with analysis run times of around 8 min. The hyphenated technique LC/LC/ESI‐MS/MS is proved to be a powerful analytical tool, allowing the rapid, sensitive and selective determination of 4‐nitrophenol and 3‐methyl‐4‐nitrophenol in human urine without any sample treatment. Copyright © 2002 John Wiley & Sons, Ltd.

A liquid chromatography/electrospray ionization-tandem mass spectrometry method for quantification of specific organophosphorus pesticide biomarkers in human urine

Article

Aug 2003

Organophosphorus pesticides are commonly used in both agricultural and residential settings. The widespread use of these chemicals makes it almost impossible for humans to avoid exposure. In order to determine background human exposure, there is a need for fast, reliable, and sensitive analytical methods. We have developed a sensitive method to quantify specific biomarkers of the organophosphorus pesticides acephate, azinphos, chlorpyrifos, coumaphos, diazinon, isazofos, malathion, methamidophos, parathion and pirimiphos or their O,O-dimethyl analogues in human urine, as their selective metabolites or as the intact pesticide. Isotopically labeled internal standards were used for eight of the analytes. The use of labeled internal standards in combination with high-performance liquid chromatography electrospray ionization-tandem mass spectrometry provided a high degree of specificity. Repeated analysis of urine samples fortified with high and low concentrations of the analytes gave relative standard deviations (RSD) of less than 10% for the analytes with an isotopically labeled standard. Analytes without isotopically labeled standards had higher RSD. For all compounds except methamidophos and acephate, the recoveries were greater than 70%. The limits of quantification for most of the analytes were in the range of 0.1 to 1 ng/mL. We detected concentrations of most of these pesticides and/or their metabolites in urine samples from non-occupationally exposed persons using our method. Our frequencies of detection for the analytes measured ranged from 1% to 98%.

Isotope Dilution High-Performance Liquid Chromatography-Tandem Mass Spectrometry Method for Quantifying Urinary Metabolites of Synthetic Pyrethroid Insecticides

Article

May 2004

This paper describes a method for measuring cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acids (cis-DCCA and trans-DCCA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (DBCA), 3-phenoxybenzoic acid (3PBA), and 4-fluoro-3-phenoxybenzoic acid (4F3PBA) in human urine. These compounds are considered to be reliable biomarkers of exposure for many pyrethroid insecticides used in the United States. In this method, stable isotopically labeled analogues of trans-DCCA and 3PBA were spiked into urine as internal standards. After solid-phase extraction, the extracts were analyzed by high-performance liquid chromatography coupled with tandem mass spectrometry using turbo ion-spray atmospheric pressure ionization. The limits of detection (LODs) ranged from 0.1 to 0.5 μg/L. Within-day relative standard deviations ranged from 1.8 to 13% and between-day relative standard deviations ranged from 0.5 to 18%. Absolute analyte recoveries ranged from 72 to 93%. Chromatographic retention times were less than 8 min. This method was used to measure urinary concentrations of these metabolites in persons with no known exposure to pyrethroids and some with suspected residential exposure. Metabolites of synthetic pyrethroids were detected in 74% of the samples analyzed. cis-DCCA, trans-DCCA, DBCA, 4F3PBA, and 3PBA were detected in 36, 50, 3, 9, and 64% of the samples analyzed, respectively.

A Liquid Chromatography-Tandem Mass Spectrometry Multiresidue Method for Quantification of Specific Metabolites of Organophosphorus Pesticides, Synthetic Pyrethroids, Selected Herbicides, and DEET in Human Urine

Abstract

No full-text available

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